A device and method for maintaining stable bus voltage during acceleration and deceleration of a ventilator turbine

Abstract

The present invention belongs to the field of medical equipment technology, and specifically relates to a device and method for maintaining the stability of a busbar power supply for the acceleration and deceleration motion of a ventilator turbine. The device comprises a brake power supply and a turbine driver, wherein the brake power supply comprises a turbine power supply, an ideal diode circuit, and a comparative bleeder; the turbine power supply is connected to the ideal diode circuit, the comparative bleeder, and the turbine driver via a busbar. The present invention addresses the problem that when a ventilator is used at high frequency and full load, frequent turbine acceleration and braking causes a rapid increase in instantaneous busbar current and voltage consumption, resulting in increased turbine wear, a reduced lifespan, prolonged braking time, and a threat to patient treatment safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical equipment, and in particular relates to a device and method for maintaining the stability of a busbar power supply for the acceleration and deceleration motion of a ventilator turbine. Background Art

[0002] Mainstream ventilators generally use a turbine drive method with a high-speed brushless DC motor (BLDCM). The speed requirement for the turbine in clinical applications is relatively high, generally 5,000 to 100,000 per minute. In order to achieve the appropriate pressure, the acceleration process from idle speed (generally less than 5,000 rpm) to the target speed should be less than 100ms, requiring the bus to provide an acceleration current several times the rated current of the turbine. During the turbine acceleration process, there will be instantaneous large current consumption, requiring the bus voltage to be very small. A large amount of energy needs to be released during the deceleration process. If the brakes are too rapid, the bus voltage will rise rapidly. Therefore, acceleration and deceleration are the difficulties of ventilator turbine drive.

[0003] Conventional ventilator designs primarily use diodes to prevent the back electromotive force (EMF) from flowing back into the front-end bus voltage source during turbine braking. When the diode conducts in the forward direction, it generates a voltage drop of 0.5V to 0.7V. This voltage drop also varies with current, resulting in significant losses on the bus.

[0004] In conventional designs, a power transient suppressor (TVS) diode is connected in parallel with the busbar to eliminate the rising back EMF. When the busbar voltage exceeds the TVS breakdown voltage, avalanche breakdown occurs, instantly short-circuiting and releasing energy, clamping the voltage at a preset voltage. The TVS is a wearable device, and each breakdown and clamping of the TVS causes damage, until the PN junction completely fails. The TVS breaks down during every respiratory cycle, significantly reducing its lifespan. Furthermore, the voltage at which breakdown and clamping occur are not always consistent, potentially causing instability in the ventilator's function. Summary of the Invention

[0005] The main purpose of the present invention is to provide a device for maintaining the stability of the bus power supply during the acceleration and deceleration movement of the ventilator turbine, so as to solve the problem that when the ventilator is used at high frequency and full load, the frequent acceleration and braking of the turbine causes the bus instantaneous current and voltage consumption to increase rapidly, resulting in increased ventilator turbine loss and reduced life, prolonged braking time, and a threat to patient treatment safety.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A device for maintaining the bus voltage stability of a ventilator turbine acceleration and deceleration movement, the device comprising a brake power supply and a turbine driver, the brake power supply comprising a turbine power supply, an ideal diode circuit and a comparative bleeder; the turbine power supply is connected to the ideal diode circuit, the comparative bleeder and the turbine driver via a bus.

[0008] Preferably, the comparative bleeder includes a precision voltage regulator D30, a comparative bleeder circuit UX1A, a diode D29, a P-channel MOS tube, a power bleeder resistor or an electric heater, a current limiting resistor R150, and filter capacitors C115-C117;

[0009] The power supply side of the busbar is connected to the output end of the precision voltage regulator tube D30 through the current limiting resistor R150, and the output end of the precision voltage regulator tube D30 is connected to the non-inverting end of the comparison and discharge circuit UX1A through the resistor R153. The inverting end of the comparison and discharge circuit UX1A is connected to the turbine driver side of the busbar through the resistor R151. The inverting end of the comparison and discharge circuit UX1A is also grounded through the resistor R157;

[0010] The output end of the comparison and discharge circuit UX1A is connected to the gate of the PMOS transistor Q9 through a resistor R152, and the resistor R152 is connected in parallel with a diode D29; the source of the PMOS transistor Q9 is connected to the turbine driver side of the busbar, and the drain of the PMOS transistor Q9 is connected to a power discharge resistor or an electric heater;

[0011] The precision voltage regulator D30 and the filter capacitor C117 are connected to ground in parallel; the non-inverting terminal and the output terminal of the comparison and discharge circuit UX1A are connected via a resistor R154; the gate and the source of the PMOS tube Q9 are connected via a resistor R149; the negative electrode of the comparison and discharge circuit UX1A is grounded, the positive electrode of the comparison and discharge circuit UX1A is connected to the power supply terminal of the bus and is connected to the filter capacitors C115 and C116 through normally closed contacts, and the filter capacitors C115 and C116 are connected to ground in parallel.

[0012] Further preferably, the power discharge resistor is a resistor R155 and a resistor R156 connected in parallel.

[0013] The ideal diode circuit comprises:

[0014] The gate drive output pin of the ideal diode controller U17 is connected to the gate of the NMOS tube Q7, the SOURCE pin of U17 is connected to the source of the NMOS tube Q7, the OUT pin of the ideal diode controller U17 is connected to the drain of the NMOS tube Q7, a Zener diode D23 is connected between the gate and source of the NMOS tube Q7 to clamp the MOS drive voltage, the IN pin, SOURCE pin and the source of the NMOS tube Q7 of the ideal diode controller U17 are connected to the power supply voltage, and the SHDN pin of the ideal diode controller U17 is connected to the power supply voltage through the resistor R142; The VSS pin of the ideal diode controller U17 is connected to the power ground through resistor R143. A ceramic capacitor C112 is connected between the OUT pin and the VSS pin of the ideal diode controller U17 for filtering. Capacitors C110 and C111 are connected in parallel between the power supply voltage and the power ground for filtering and providing instantaneous current. At the same time, TVS tubes D25 and D24 are connected between the power supply and the ground. A power diode D22 is connected in parallel between the source and drain of the NMOS tube Q7. The voltage output by the drain of the NMOS tube Q7 is the bus voltage, which is connected to the ground in parallel through capacitors C105 and C106 for filtering and providing instantaneous output capability.

[0015] Preferably, the brake power supply includes a diode circuit, and the diode is an ideal diode. In the brake power supply, the ideal diode provides unidirectional power supply, preventing the bus voltage from flowing back to the power supply voltage, while the comparative bleeder circuit reduces the raised bus voltage to a normal level. Therefore, the two need to be used in combination.

[0016] The present invention also provides a method for maintaining the stability of the bus voltage of the ventilator turbine acceleration and deceleration movement based on the above device, the method comprising the following steps:

[0017] The set discharge voltage is higher than the normal working bus voltage. When the turbine brakes, the bus voltage rises higher than the discharge voltage, the comparative bleeder opens, and the energy generated by the turbine brake is discharged through the power discharge resistor or used for heating the electric heater.

[0018] This invention replaces the conventional diode in the brake circuit of the brake power supply with an ideal diode, using a MOS transistor driver plus an N-channel MOS transistor. An ideal diode is a designed circuit consisting of a dedicated MOS transistor driver and a MOS transistor. Because it achieves the unidirectional conductivity and reverse blocking characteristics of a diode while avoiding the large voltage drop when the diode is turned on, it is called an ideal diode and is commercially available. The ideal diode can control the voltage drop across the MOS transistor to 30mV, and the DC resistance (Rds) of the power N-channel MOS transistor can be less than 2mΩ.

[0019] When a patient exhales, the turbine must quickly reduce its speed to a level below the positive end-expiratory pressure (PEEP). If this switching time is prolonged, the patient may experience difficulty in exhaling, increasing the risk of patient-ventilator conflict. Therefore, high-performance ventilators typically control the speed reduction process within 100ms.

[0020] The turbine is transformed from an electric motor into a generator, and the back electromotive force generated is superimposed on the bus voltage, causing the bus voltage to rise. Therefore, an ideal diode is designed at the power supply end of the bus voltage to prevent the power supply end of the bus voltage from triggering protection. However, the ideal diode is unidirectional, and this part of the energy cannot be released through the power supply voltage, but can only be released through the turbine driver and the turbine, which may trigger the driver protection, reduce the life of the turbine, and prolong the braking process. The present invention adds a discharge circuit to the bus at the rear end of the ideal diode, and the high voltage generated during braking is released through the discharge circuit, thereby maintaining the bus voltage stable. The limit value of the discharge voltage must be slightly higher than the bus voltage, otherwise the discharge circuit will keep working, resulting in the consumption of bus voltage even during normal operation, generating additional power consumption.

[0021] The present invention adopts a comparative bleeder. When the bus voltage is higher than 25.4V (the normal working bus voltage is 24V), the comparative bleeder is started to work, and the bleed current is equal to the bus voltage V m / (R 155 / / R 156 ). Compare the bleeder reference voltage V ref Set at 10V, the present invention uses LM4040-10 precision regulator, V ref The setting value of is related to the bus voltage and should be operated near the middle value of the comparison bleeder supply voltage. The supply voltage of the comparison bleeder of the present invention is the bus voltage. The normal bus voltage is 24V, so the reference value is selected as 10V. This allows the comparison circuit to work optimally, which is based on the error calculation perspective.

[0022] Set the discharge voltage Vd, then Vref = Vd * (R153 / (R153 + R151)). Set R153 = R151 * Vref / (Vd - Vref), and fix R151 = 10K. Calculate the value of R153, then query the E96 and E24 series resistor values, select the resistor value closest to R153, and then verify that the Vd value meets the requirements. These resistors are selected with 1% accuracy. Calculate the maximum error to ensure that the Vd value at both extremes is higher than the normal operating bus voltage, while also ensuring that the Vd value does not exceed the bus voltage significantly.

[0023] After setting the parameters, when the turbine brakes, the bus voltage rises above 25.4V, the comparative bleeder opens, and the energy generated by the brake is discharged through the power resistors R155 and R156. When the bus voltage is lower than 25.4V, the comparative bleeder closes, and the D29 diode accelerates the shutdown, turning off the MOS tube Q9 and closing the discharge path. If you are worried that the back electromotive force will continue to rebound, causing the discharge circuit to start frequently, you can use a hysteresis comparative bleeder and select a suitable resistance value for R154, which will not be discussed here. After adopting the present invention, the actual maximum voltage of the tested Vd value is maintained at 26V after continuous operation for 24 hours at room temperature. If this discharge circuit is removed, the actual test of the bus voltage reaches 74V. The surface temperature of the power resistor of the discharge circuit is maintained at 55°C under natural air cooling conditions.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Using an ideal diode instead of the original ordinary diode solution can achieve arbitrary switching of the ventilator turbine between 5000 and 40000 rpm with a cycle of 2s. After working for 24 hours at room temperature, the surface temperature of the MOS tube is maintained at 43°C and the surface temperature of the diode is around 80°C, which improves the reliability and practicality of the ventilator.

[0026] 2. Adding a discharge circuit to the busbar can reduce the maximum busbar voltage of about 74V to 26V during the ventilator turbine braking and acceleration process (the measured value after 24 hours of continuous operation at room temperature).

[0027] This invention addresses the practical challenges faced by ventilator turbine drive circuits in tumor radiotherapy applications. Considering the frequent on / off switching required to assist large numbers of lung cancer patients in achieving rhythmic breathing during radiotherapy, the present invention optimizes existing circuit designs, resolving the challenges of accelerating and braking during these frequent on / off cycles and facilitating expansion into other application scenarios. This improves the practicality of portable ventilators in clinical tumor radiotherapy applications, addresses practical challenges encountered during application, and enhances their effectiveness and reliability in new application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the device for maintaining the stability of the busbar power supply for the acceleration and deceleration movement of the ventilator turbine of the present invention;

[0029] Figure 2 It is a structural schematic diagram of a comparative bleeder of the present invention;

[0030] Figure 3 This is a circuit diagram of an ideal diode of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] like Figure 1-Figure 3 As shown, a device for maintaining the bus voltage stability of the acceleration and deceleration movement of a ventilator turbine, the device includes a brake power supply and a turbine driver, the brake power supply includes a turbine power supply, an ideal diode circuit and a comparative bleeder; the turbine power supply is connected to the ideal diode circuit, the comparative bleeder and the turbine driver through a bus.

[0034] The comparative bleeder includes a precision voltage regulator D30, a comparative bleeder circuit UX1A, a diode D29, a P-channel MOS tube, a power bleeder resistor or an electric heater, a current limiting resistor R150, and filter capacitors C115-C117;

[0035] The power supply side of the busbar is connected to the output end of the precision voltage regulator tube D30 through the current limiting resistor R150, and the output end of the precision voltage regulator tube D30 is connected to the non-inverting end of the comparison and discharge circuit UX1A through the resistor R153. The inverting end of the comparison and discharge circuit UX1A is connected to the turbine driver side of the busbar through the resistor R151. The inverting end of the comparison and discharge circuit UX1A is also grounded through the resistor R157;

[0036] The output end of the comparison and discharge circuit UX1A is connected to the gate of the PMOS transistor Q9 through a resistor R152, and the resistor R152 is connected in parallel with a diode D29; the source of the PMOS transistor Q9 is connected to the turbine driver side of the busbar, and the drain of the PMOS transistor Q9 is connected to a power discharge resistor or an electric heater;

[0037] The precision voltage regulator D30 and the filter capacitor C117 are connected to ground in parallel; the non-inverting terminal and the output terminal of the comparison and discharge circuit UX1A are connected via a resistor R154; the gate and the source of the PMOS tube Q9 are connected via a resistor R149; the negative electrode of the comparison and discharge circuit UX1A is grounded, the positive electrode of the comparison and discharge circuit UX1A is connected to the power supply terminal of the bus and is connected to the filter capacitors C115 and C116 through normally closed contacts, and the filter capacitors C115 and C116 are connected to ground in parallel.

[0038] The power discharge resistor is a resistor R155 and a resistor R156 connected in parallel.

[0039] A method for maintaining a stable bus voltage during acceleration and deceleration of a ventilator turbine based on the above device, the method comprising the following steps:

[0040] The set discharge voltage is higher than the normal working bus voltage. When the turbine brakes, the bus voltage rises higher than the discharge voltage, the comparative bleeder opens, and the energy generated by the turbine brake is discharged through the power discharge resistor or used for heating the electric heater.

[0041] In this embodiment, if Figure 2 As shown, D30 is a precision voltage regulator, which stabilizes the voltage to 10V, UX1A is a comparative bleeder, D29 is a diode (non-voltage regulator diode), Q9 is a P-channel MOS tube, R155 and R156 are power bleeder resistors, and the two are used in parallel to reduce the power dissipation of a single resistor. The value determines the size of the bleeder current.

[0042] The input voltage is connected to the precision voltage regulator D30 through a current-limiting resistor R150. The size of the current-limiting resistor depends on the input voltage and the operating current of the voltage regulator. R150 = (input power supply voltage PWBUS - voltage regulator circuit voltage of the voltage regulator) / operating current of the voltage regulator. The output of the precision voltage regulator D30 is connected to the non-inverting terminal of the comparator bleeder circuit UX1A through a resistor R153. The inverting terminal of the comparator bleeder circuit UX1A is connected to the bus voltage divided by resistors R151 and R157. The calculation of R151, R157, and R153 is described above. The UX1A is a general-purpose comparator bleeder; any device with a maximum supply voltage higher than the circuit's input voltage can be used. Capacitors C117, C115, and C116 are filter capacitors for the input and power supply of the comparison bleeder. The output end of the comparison bleeder circuit UX1A is connected to the G (gate) electrode of the PMOS tube Q9 in parallel through the resistor R152 and the diode D29. The S (source) electrode of the PMOS tube Q9 is connected to the bus voltage, and the D (drain) electrode is connected to the bleeder resistor.

[0043] In this embodiment, Figure 3As shown, U17 LTC4359 is an ideal diode controller. U17's gate drive output pin (GATE) is connected to the gate of NMOS transistor Q7, U17's source terminal (SOURCE) is connected to Q7's source, U17's OUT pin is connected to Q7's drain, and a 12V Zener diode is connected between the gate and source to clamp the MOS drive voltage. U17's IN pin, SOURCE pin, and NMOS Q7's source are connected to the power supply voltage. U17's SHDN pin is connected to the power supply voltage through a 10K resistor R142. U17's VSS pin is connected to the power supply ground through a 1K resistor R143. A 104 ceramic capacitor C112 is connected between U17's OUT pin and VSS pin for filtering. Capacitors C110 and C111 are connected in parallel between the power supply voltage and the power ground for filtering and transient current. These two capacitors should be located near the NMOS transistor. TVS diodes D25 and D24 are connected between the power supply and ground, one near the power input and the other near the NMOS transistor. A power diode D22 is connected in parallel between the source and drain of the NMOS transistor Q7 to enhance the flow capacity of Q7's internal body diode and provide better freewheeling current. The voltage output by Q7's drain is the bus voltage PMOTOR, which is connected in parallel to ground via capacitors C105 and C106 for filtering and transient output capability.

[0044] The ideal diode and brake circuit combine to form the BLDC power supply, suitable for all turbine ventilators. Simply adjust the comparator threshold and bleeder resistor. The bleeder resistor can also be omitted. If the device has a heating function, the bleeder resistor can be omitted and a heater can be connected instead.

[0045] The process parameters (such as temperature, time, etc.) of the present invention can realize the method by taking upper and lower limits and interval values, and the embodiments are not listed here one by one.

[0046] Any content not described in detail in the present invention can be based on conventional technical knowledge in the art.

[0047] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions 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 embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A device for maintaining the bus voltage stability of a ventilator turbine acceleration and deceleration movement, the device comprising a brake power supply and a turbine driver, characterized in that: The brake power supply includes a turbine power supply, an ideal diode circuit and a comparative bleeder; the turbine power supply is connected to the ideal diode circuit, the comparative bleeder and the turbine driver via a bus; The comparative bleeder includes a precision voltage regulator D30, a comparative bleeder circuit UX1A, a diode D29, a PMOS tube Q9, a power bleeder resistor or an electric heater, a current limiting resistor R150, and filter capacitors C115-C117; The power supply side of the busbar is connected to the output end of the precision voltage regulator tube D30 through the current limiting resistor R150, and the output end of the precision voltage regulator tube D30 is connected to the non-inverting end of the comparison and discharge circuit UX1A through the resistor R153. The inverting end of the comparison and discharge circuit UX1A is connected to the turbine driver side of the busbar through the resistor R151. The inverting end of the comparison and discharge circuit UX1A is also grounded through the resistor R157; The output end of the comparison and discharge circuit UX1A is connected to the gate of the PMOS transistor Q9 through a resistor R152, and the resistor R152 is connected in parallel with a diode D29; the source of the PMOS transistor Q9 is connected to the turbine driver side of the busbar, and the drain of the PMOS transistor Q9 is connected to a power discharge resistor or an electric heater; The precision voltage regulator D30 and the filter capacitor C117 are connected to ground in parallel. The in-phase terminal and the output terminal of the comparison and discharge circuit UX1A are connected via a resistor R154. The gate and source of the PMOS tube Q9 are connected via a resistor R149. The negative electrode of the comparison and discharge circuit UX1A is grounded, and the positive electrode of the comparison and discharge circuit UX1A is connected to the power supply terminal of the bus and connected to the filter capacitors C115 and C116 through the normally closed contacts. The filter capacitors C115 and C116 are connected to ground in parallel. The size of the current limiting resistor R150 depends on the input voltage and the operating current of the Zener diode. R150 = (input power supply voltage PWBUS - Zener diode voltage regulator circuit voltage) ÷ Zener diode operating current.

2. The device according to claim 1, characterized in that The power discharge resistor is a resistor R155 and a resistor R156 connected in parallel.

3. The device according to claim 1, characterized in that The ideal diode circuit comprises: The gate drive output pin of the ideal diode controller U17 is connected to the gate of the NMOS tube Q7, the SOURCE pin of U17 is connected to the source of the NMOS tube Q7, the OUT pin of the ideal diode controller U17 is connected to the drain of the NMOS tube Q7, a Zener diode D23 is connected between the gate and source of the NMOS tube Q7 to clamp the MOS drive voltage, the IN pin, SOURCE pin and the source of the NMOS tube Q7 of the ideal diode controller U17 are connected to the power supply voltage, and the SHDN pin of the ideal diode controller U17 is connected to the power supply voltage through the resistor R142; The VSS pin of the ideal diode controller U17 is connected to the power ground through resistor R143. A ceramic capacitor C112 is connected between the OUT pin and the VSS pin of the ideal diode controller U17 for filtering. Capacitors C110 and C111 are connected in parallel between the power supply voltage and the power ground for filtering and providing instantaneous current. At the same time, TVS tubes D25 and D24 are connected between the power supply and the ground. A power diode D22 is connected in parallel between the source and drain of the NMOS tube Q7. The voltage output by the drain of the NMOS tube Q7 is the bus voltage, which is connected to the ground in parallel through capacitors C105 and C106 for filtering and providing instantaneous output capability.

4. A method for maintaining a stable bus voltage during acceleration and deceleration of a ventilator turbine based on the device of any one of claims 1 to 3, the method comprising the following steps: The set discharge voltage is higher than the normal working bus voltage. When the turbine brakes, the bus voltage rises higher than the discharge voltage, the comparative bleeder opens, and the energy generated by the turbine brake is discharged through the power discharge resistor or used for heating the electric heater.

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