Multi-pulse excitation generation circuit and control method
By combining multiple energy storage capacitors and switching devices, the problem of single pulse width in existing magnetic stimulation devices has been solved, enabling flexible adjustment of multiple pulse widths and frequencies, thus improving treatment efficacy and safety.
Patent Information
- Application Number
- CN202610303935.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-08
AI Technical Summary
Existing magnetic stimulation devices have a single pulse width for the magnetic field, which cannot be flexibly adjusted, resulting in limited treatment effects and patient comfort. Furthermore, replacing the excitation coil can easily lead to increased contact resistance and device damage.
By combining multiple energy storage capacitors and switching devices, the capacitance value of the energy storage capacitors can be adjusted through the control module to achieve flexible adjustment of multi-pulse width and frequency, avoiding the need for manual replacement of the excitation coil.
It enables flexible adjustment of multi-pulse width and frequency, improving the flexibility and safety of treatment effects and reducing the risk of device damage.
Smart Images
Figure CN122001341A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power electronics technology, and in particular to a multi-pulse excitation generating circuit and control method. Background Technology
[0002] The principle of pulsed magnetic stimulation is to charge the energy storage capacitor with DC power. After charging to a certain voltage, the thyristor module acts as a solid-state relay to switch and discharge the excitation coil. The discharge current is several kA, generating a pulsed magnetic field in units of T. This provides non-contact, non-invasive deep treatment to the human body. The current waveform of a single discharge is a complete sine wave current of one positive and negative half-cycle, with a period that is the reciprocal of the resonant frequency (F0=1 / (2π√(LC))). The generated pulsed magnetic waveform is consistent with the current waveform, and the pulse width is 1 / 2 cycle.
[0003] Current magnetic stimulation products output a single pulse width, which can only change the frequency of the output pulse train to alter the patient's sensation and treatment effect. Conventional equipment typically contains only one energy storage capacitor and one excitation coil. Some excitation coils may be configured with two to act on different parts of the body. Furthermore, changing the output pulse width requires manual replacement of the coil. This is because during the discharge process, the discharge circuit generates thousands of amperes of current, which places very strict requirements on the equivalent DC resistance of the wires between key components, including the terminals. The resistance is usually below 0.5mΩ. Excessive contact resistance can cause severe localized heating, which can lead to overheating and damage to the components. Therefore, the energy storage capacitor is placed inside the equipment and cannot be replaced by the operator at will.
[0004] Because the energy storage capacitor and excitation coil are single, the generated magnetic field pulse width is also single. At most, only 2-3 excitation coils are equipped, resulting in only 2-3 pulse width outputs. Different pulse widths of the pulse magnetic field have different therapeutic effects. Pulse width is one of the key parameters determining the stimulation effect and patient experience. It directly affects the depth of treatment, the type of neuromuscular activation, and the patient's tolerance. The core principle is the "selective activation" of nerve fibers by pulse width. Nerve fibers have different diameters and types, and their sensitivity to pulse width varies: thinner nerve fibers (such as Aδ fibers and C fibers that innervate sensation, as well as autonomic nerves) are more sensitive to wider pulse widths and are more easily activated; thicker motor nerve fibers (Aα fibers) and muscle fibers respond well to narrower pulse widths. Summary of the Invention
[0005] The purpose of this invention is to address the problems existing in the background technology by proposing a multi-pulse excitation generation circuit and control method.
[0006] The technical solution of the present invention, in its first aspect, provides a multi-pulse excitation generating circuit and control method, comprising: A charging module is used to convert AC voltage to DC voltage. Energy storage capacitors can be configured with multiple different capacitance values; Switching devices corresponding to each energy storage capacitor are used to control whether each energy storage capacitor is connected to the main energy storage circuit. The control module is used to control the on / off state of each switching device; The excitation coil is used for energy conversion, converting the electrical energy released by the energy storage capacitor into a pulsed magnetic field; The discharge thyristor module is used to control the discharge of the energy storage capacitor to the excitation coil; The voltage acquisition module is used to acquire the voltage of each energy storage capacitor; The control module controls the combination state of the corresponding switching devices according to the preset pulse width selection signal, changes the capacitance value of the total energy storage capacitor, and realizes the adjustment of the output pulse width.
[0007] Preferably, the charging module is electrically connected to multiple energy storage capacitors and uses DC voltage to charge the energy storage capacitors.
[0008] Preferably, each energy storage capacitor is connected in parallel to the total energy storage capacitor using a switching device; by controlling the switching state of the switching devices, a total of 2... n -1 is the total energy storage capacitor with different capacitance values; n is the number of energy storage capacitors.
[0009] Preferably, the 100µs trigger signal output by the control module passes through the isolation transformer T1 and triggers the thyristor module SCR1 to conduct. The energy storage capacitor, the excitation coil L1, and the thyristor module SCR1 form a discharge circuit. The maximum discharge current IMax≈Vc / XL=Vc / 2πFL, the resonant frequency F=1 / (2π√(LC)), and the pulse width=1 / 2F. After the discharge current passes through one sine wave cycle, the current crosses zero and the thyristor is cut off and conduction stops, thus stopping the discharge. One trigger signal generates one positive and one negative pulse output.
[0010] Preferably, the energy storage capacitor uses a high-voltage film capacitor with an ESR of less than 5mΩ.
[0011] Preferably, the switching device is one of a mechanical relay, a solid-state relay, a bidirectional thyristor, or a dual IGBT.
[0012] Preferably, the four capacitors C1 to C4 are connected in parallel to the total energy storage capacitor using four relays K1 to K4 respectively; the control module controls the state of the four relays to control the total capacitance of the energy storage capacitor and change the output pulse width.
[0013] Preferably, bidirectional thyristors D1~D4 are used as switches. The control module controls the drive isolation transformers T2~T5. After the output is rectified and filtered, D1~D4 is triggered to conduct. After the drive of T2~T5 is stopped, T2~T5 has no output, and D1~D4 is turned off.
[0014] Preferably, two IGBTs Q1 and Q2 are connected in series as a switch. The control module controls the drive isolation transformer T8. After the output is rectified and filtered, Q1 and Q2 are triggered to conduct simultaneously. After the drive of T8 is stopped, T8 has no output, and Q1 and Q2 are turned off simultaneously. The other three groups of IGBTs are controlled to turn on and off in the same way.
[0015] A second aspect of the present invention provides a control method for a multi-pulse excitation generating circuit, comprising the following steps: S1. Control the charging module to charge multiple energy storage capacitors; S2. Based on the target pulse width, control the combined state of multiple switching devices and select the capacitor combination connected to the total energy storage circuit; S3. Before discharging, check the voltage of each energy storage capacitor. If there is a voltage difference, perform voltage equalization. S4. The discharge thyristor module is turned on, causing the energy storage capacitor to discharge through the excitation coil and generate a pulsed magnetic field. S5. By controlling the combination of switching devices, outputs with different pulse widths can be achieved.
[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention breaks through the limitations of traditional pulsed magnetic single-pulse-width output, achieving adjustable pulse width, adjustable pulse frequency, and adjustable output intensity, enabling "selective activation" of different nerve fibers, and synergistic effects with stimulation frequency and intensity: ① High intensity + wide pulse: produces a deeper and stronger neuromodulation effect; ② Low frequency (e.g., 1Hz) + wide pulse: often used to produce an inhibitory effect (analgesia); ③ High frequency (e.g., 20-50Hz) + narrow pulse: often used to produce an excitatory effect (muscle strength training); This invention changes the output pulse width without the need for manual replacement of the energy storage capacitor and excitation coil. The pulse width is adjustable in multiple levels. It does not require disassembling the excitation coil, which can reduce the risk of overheating and damage caused by aging due to the long-term plugging and unplugging of the terminals. However, one coil corresponds to one pulse width, which cannot achieve free switching and adjustable output of multiple pulse widths. This invention allows setting multiple pulse widths and multiple frequency combinations for output recipes on the device. After selecting an output recipe, the control module can automatically switch between different pulse widths and different frequency combinations for output according to the recipe, without the need for manual stopping of operation before switching. This invention uses multiple switching devices to connect the energy storage capacitor in parallel in the total discharge circuit, which can divert the total current to multiple switching devices, thus making the maximum current requirement of the switching devices less stringent. This invention uses 3 capacitors to create 7 pulse widths, 4 capacitors to create 15 pulse widths, and 5 capacitors to create 31 pulse widths. The number of pulse width combinations increases exponentially with the number of capacitors. Attached Figure Description
[0017] Figure 1 This is a topology diagram of the present invention using relay control of the adjustable pulse width of a magnetic pulse. Figure 2 This is a topology diagram of the present invention using bidirectional thyristors to control the pulse magnetic adjustable pulse width; Figure 3 This is a topology diagram of the present invention using dual IGBTs to control the pulse magnetic adjustable pulse width. Detailed Implementation
[0018] Example 1 The purpose of this invention is to provide a method that allows for the output of different magnetic field pulse widths, as well as multiple combinations of pulse widths and frequencies, without disassembly or manual replacement of the energy storage capacitor and excitation coil, and with only a single excitation coil. This covers a range from narrow pulses to medium pulses to wide pulses, thereby achieving selective stimulation of nerve fibers, resulting in better therapeutic effects and a richer therapeutic experience.
[0019] To achieve the above objectives, the present invention adopts the following technical solution: An adjustable pulse width control method for a pulse magnetic stimulation therapy device includes a charging module, an energy storage capacitor and switching devices, a voltage acquisition module, a control module, an excitation coil, and a discharge thyristor module. The energy storage capacitor and switching devices incorporate four energy storage capacitors with different capacitance values. Each energy storage capacitor is controlled by a switching device (including mechanical relays, solid-state relays, bidirectional thyristors, and dual IGBTs) and connected in parallel to the total energy storage capacitor. By changing the closing state of the four switches, 15 different total capacitance values can be combined, thus outputting 15 different pulse widths. If five capacitors and five switches are used, 31 combinations can be achieved. The number of capacitors and the number of combinations are exponentially related; for example, if the number of capacitors is N, the number of combinations is 2^N - 1. Removing the state of being completely open with zero capacitance, the capacitance values of each capacitor are twice that of the others to avoid value duplication and ensure a linear increase in the total capacitance. The table below calculates the pulse width using a 50uH excitation coil. Table 1. Comparison Table for Calculating the Pulse Width of a 50uH Excitation Coil ; The above method uses four capacitors to cover an output range from a narrow pulse of 140µs to a wide pulse of 544µs. To achieve an even wider range, adjust the minimum and maximum total capacitance values. For more pulse width options, increase the number of capacitors, or equip two excitation coils to double the output pulse width combination. This can be flexibly adjusted according to different product positioning requirements. Different pulse widths can be applied to different fields; for example, narrow pulses of 50µs-200µs can be used in skeletal muscles (pelvic floor muscles) and large motor nerves, medium pulses of 200µs-500µs can be used for mixed effects of motor nerves and some sensory nerves, and wide pulses of 500µs-1000µs can be used in fine sensory nerve fibers, pain transmission pathways, and autonomic nerves.
[0020] Please see Figure 1 As shown, the adjustable pulse width control method circuit of the pulse magnetic stimulation therapy device of the present invention includes a charging module, a voltage acquisition module, a control module, an energy storage capacitor, a switching device, an excitation coil L1, and a discharge thyristor module SCR1. The charging module boosts the AC voltage of the power grid to DC voltage and outputs it to charge the energy storage capacitor. The voltage acquisition module collects the voltage of the energy storage capacitor and stops charging after reaching the set target voltage. The control module outputs a 100uS trigger signal, which, after passing through the isolation transformer T1, triggers the control thyristor module SCR1 to conduct. The energy storage capacitor, the excitation coil L1, and the thyristor module SCR1 form a discharge circuit. The maximum discharge current IMax≈Vc / XL=Vc / 2πFL, the resonant frequency F=1 / (2π√(LC)), and the pulse width =1 / 2F. After the discharge current passes through one sine wave cycle, the thyristor is cut off and conduction stops the discharge when the current crosses zero. One trigger signal generates one positive and one negative pulse output. Four capacitors C1-4 are connected in parallel to the total energy storage capacitor using four relays K1-K4. These four relays can generate a total of 16 states. After removing the fully open state, there are 15 possible combinations. The control module controls the states of the four relays to control the total capacitance of the energy storage capacitor, thereby changing the output pulse width. The capacitance values of capacitors C1-4 increase by a factor of two to ensure that no combination is repeated, and the total capacitance value of all combinations increases linearly (as shown in Table 1). The capacitance values of C1-4 do not necessarily need to increase by a factor of two; as long as all combinations produce different results, the same effect can still be achieved.
[0021] The energy storage capacitors used need to be high-voltage film capacitors with extremely low ESR, typically below 5mΩ, to ensure low losses during discharge. Under these conditions, the relay cannot close and switch when there is a voltage difference between the energy storage capacitors. Otherwise, the relay contacts will experience transient high current and arcing when closing, leading to relay damage. To address this issue, a voltage acquisition module should be used to identify the voltage of capacitors C1-4 before the relay closes and switches. If a voltage difference exists, the capacitors with the voltage difference should be charged and discharged to balance the voltage between them. Only after the voltage difference between the capacitors that need to be connected to the total energy storage capacitor is within a safe range should the relay close. Closing the relay within a reasonable differential voltage range can prevent relay arcing, overcurrent, and other abnormal phenomena, thus protecting the relay and ensuring safe and reliable switching.
[0022] In the circuit described above, the capacitance of the energy storage capacitor and the inductance of the excitation coil are not limited; the output pulse width range can be adjusted by changing these values. Similarly, the number of capacitors and relays is not limited; the number of capacitors and the number of adjustable pulse widths can be increased or decreased depending on the product's positioning, with an exponential relationship between the two.
[0023] Example 2 like Figure 2 The diagram shows the second type of circuit with adjustable pulse width, and its overall principle is similar to... Figure 1 Similarly, bidirectional thyristors D1~4 are used as switches. The control module controls the drive isolation transformers T2~T5. After the output is rectified and filtered, D1~4 is triggered to conduct. After stopping the drive of T2~T5, T2~T5 has no output, and D1~D4 is turned off.
[0024] Example 3 like Figure 3 The diagram shows the third type of circuit with adjustable pulse width, whose overall principle is similar to... Figure 1 Similarly, two IGBTs, Q1 and Q2, are connected in series as a switch. The control module controls the drive isolation transformer T8. After the output is rectified and filtered, Q1 and Q2 are triggered to conduct simultaneously. After stopping the drive of T8, T8 has no output, and Q1 and Q2 are turned off simultaneously. The other three groups of IGBTs are controlled to turn on and off in the same way.
[0025] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.
Claims
1. A multi-pulse excitation generating circuit and control method, characterized in that, include: A charging module is used to convert AC voltage to DC voltage. Energy storage capacitors can be configured with multiple different capacitance values; Switching devices corresponding to each energy storage capacitor are used to control whether each energy storage capacitor is connected to the main energy storage circuit. The control module is used to control the on / off state of each switching device; The excitation coil is used for energy conversion, converting the electrical energy released by the energy storage capacitor into a pulsed magnetic field; The discharge thyristor module is used to control the discharge of the energy storage capacitor to the excitation coil; The voltage acquisition module is used to acquire the voltage of each energy storage capacitor; The control module controls the combination state of the corresponding switching devices according to the preset pulse width selection signal, changes the capacitance value of the total energy storage capacitor, and realizes the adjustment of the output pulse width.
2. The multi-pulse excitation generating circuit according to claim 1, characterized in that, The charging module is electrically connected to multiple energy storage capacitors and charges the energy storage capacitors using DC voltage.
3. The multi-pulse excitation generating circuit according to claim 1, characterized in that, Each energy storage capacitor is connected in parallel to the total energy storage capacitor using a switching device; by controlling the switching state of the switching devices, a total of 2... n -1 is the total energy storage capacitor with different capacitance values; n is the number of energy storage capacitors.
4. The multi-pulse excitation generating circuit according to claim 1, characterized in that, The control module outputs a 100µs trigger signal, which, after passing through the isolation transformer T1, triggers the control thyristor module SCR1 to conduct. The energy storage capacitor, excitation coil L1, and thyristor module SCR1 form a discharge circuit. The maximum discharge current IMax≈Vc / XL=Vc / 2πFL, the resonant frequency F=1 / (2π√(LC)), and the pulse width=1 / 2F. After the discharge current passes through one sine wave cycle, the current crosses zero, the thyristor is cut off, and the discharge stops. One trigger signal generates one positive and one negative pulse output.
5. The multi-pulse excitation generating circuit according to claim 1, characterized in that, The energy storage capacitor uses a high-voltage film capacitor with an ESR of less than 5mΩ.
6. The multi-pulse excitation generating circuit according to any one of claims 1-5, characterized in that, The switching device is one of the following: mechanical relay, solid-state relay, bidirectional thyristor, or dual IGBT.
7. The multi-pulse excitation generating circuit according to claim 6, characterized in that, Four capacitors C1 to C4 are connected in parallel to the total energy storage capacitor using four relays K1 to K4 respectively; the control module controls the state of the four relays to control the total capacitance of the energy storage capacitor and change the output pulse width.
8. The multi-pulse excitation generating circuit according to claim 6, characterized in that, Using bidirectional thyristors D1~D4 as switches, the control module controls and drives isolation transformers T2~T5. After the output is rectified and filtered, D1~D4 is triggered to conduct. After stopping the drive of T2~T5, T2~T5 has no output, and D1~D4 is turned off.
9. The multi-pulse excitation generating circuit according to claim 6, characterized in that, Two IGBTs, Q1 and Q2, are connected in series as a switch. The control module controls the drive isolation transformer T8. After the output is rectified and filtered, Q1 and Q2 are triggered to conduct simultaneously. After the drive of T8 is stopped, T8 has no output, and Q1 and Q2 are turned off simultaneously. The other three groups of IGBTs are controlled to turn on and off in the same way.
10. A control method for a multi-pulse excitation generating circuit, controlling the excitation generating circuit according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Control the charging module to charge multiple energy storage capacitors; S2. Based on the target pulse width, control the combined state of multiple switching devices and select the capacitor combination connected to the total energy storage circuit; S3. Before discharging, check the voltage of each energy storage capacitor. If there is a voltage difference, perform voltage equalization. S4. The discharge thyristor module is turned on, causing the energy storage capacitor to discharge through the excitation coil and generate a pulsed magnetic field. S5. By controlling the combination of switching devices, outputs with different pulse widths can be achieved.