Circuit system for driving inductive load by switching power supply

Abstract

The utility model provides a circuit system for driving an inductive load by a switching power supply. The circuit system comprises the switching power supply and the inductive load, the pulse voltage suppression module, the reverse electromotive force isolation module and the reverse electromotive force absorption module are connected between the switching power supply and the inductive load; the switching power supply, the inductive load, the pulse voltage suppression module, the reverse electromotive force isolation module and the reverse electromotive force absorption module are connected in the same circuit. According to the utility model, the technical problem that the operation of driving the inductive load by the switching power supply is difficult in the prior art is solved, and the reverse electromotive force generated by the inductive load is blocked and cannot reach the switching power supply by utilizing the unidirectional conductivity of the pulse voltage suppression module. And meanwhile, weak surge voltage transmitted from leakage current generated by the pulse voltage suppression module to the output end of the switching power supply is suppressed. The reverse electromotive force absorption module is used for absorbing part of reverse electromotive force current, reducing reverse electromotive force voltage and lowering the reverse withstand voltage requirement of the reverse electromotive force isolation module.

Description

Technical Field

[0001] The utility model relates to the technical field of inductive load driving, in particular to a circuit system for driving an inductive load with a switching power supply. Background Art

[0002] It has always been a difficult problem in the industry for ordinary power supplies to drive inductive loads. When inductive loads are working, especially brushed and brushless motors, due to their own equivalent inductance, a reverse electromotive force that is several times the power supply voltage will be generated at the moment the current starts and stops. The reverse electromotive force and the voltage output by the power supply are superimposed and act on the output end of the power supply. At present, in order to reduce cost and volume in circuit applications, switching power supplies are basically used. However, since switching power supplies lack large-capacity capacitors at the output port, when connected to inductive loads, they are often damaged due to the impact of reverse electromotive force.

[0003] In order to enable a switching power supply to drive an inductive load, the prior art has tried various methods.

[0004] The first method is to add a large-capacity filter capacitor at the output end of the switching power supply to absorb the reverse electromotive force of the inductive load. This method has certain limitations. If the capacity of the large-capacity filter capacitor is too small, it will not absorb the reverse electromotive force. If the capacity is too large, the starting current of the switching power supply will be too large, and the switching power supply may even fail to start.

[0005] The second method is to add a battery to the output end of the switching power supply to absorb the reverse electromotive force. When the reverse electromotive force of the inductive load is generated, it can be converted into the charging current of the battery, so the voltage of the reverse electromotive force is limited to the charging voltage at both ends of the battery, thereby protecting the switching power supply. This method is large in size due to the addition of a battery, and the battery needs regular maintenance. The battery is easy to become ineffective and lose the ability to absorb reverse electromotive force.

[0006] The third method is to connect a resistor in parallel to the output of the switching power supply to absorb the energy of the reverse electromotive force. This requires adding a set of load judgment circuits to monitor the voltage on the output of the switching power supply and the inductive load in real time. When the reverse electromotive force voltage is generated, the resistor is connected in parallel to the circuit to absorb the reverse electromotive force. When the reverse electromotive force voltage is not detected in the circuit, the resistor is disconnected. The control circuit load requires a judgment action time to connect the resistor, and the reaction speed is slow. Utility Model Content

[0007] The utility model aims to at least solve the technical problem in the prior art that it is difficult to operate a switching power supply to drive an inductive load, and in particular innovatively proposes a circuit system for driving an inductive load with a switching power supply.

[0008] In order to achieve the above-mentioned purpose of the utility model, the utility model provides a circuit system for a switching power supply to drive an inductive load, including a switching power supply and an inductive load; the output end of the switching power supply is connected to one end of a pulse voltage suppression module and one end of a reverse electromotive force isolation module, the other end of the pulse voltage suppression module is connected to the inductive load and one end of a reverse electromotive force absorption module, the other end of the inductive load is connected in sequence to the other end of the reverse electromotive force absorption module and the other end of the reverse electromotive force isolation module, and the other end of the reverse electromotive force isolation module is connected to the power ground of the switching power supply.

[0009] In a preferred implementation manner of the present invention, the switching power supply is a DC-DC module, and its model is LDFE75-48S24PS.

[0010] The DC-DC module is a small to medium power switching power supply, that is, the 48V DC power supply is converted into 24V through the DC-DC power supply module.

[0011] In a preferred embodiment of the present invention, the pulse voltage suppression module is a transient voltage suppression diode D2, whose model is SMCJ24A; the reverse electromotive force isolation module is a Schottky diode D1; and the reverse electromotive force absorption module is an electrolytic capacitor C4.

[0012] The Schottky diode D1 is a unidirectional conductive device, and the transient voltage suppression diode D2 is a voltage limiting device. By utilizing the unidirectional conductivity of the Schottky diode, the switching power supply can normally output current to the inductive load, and the reverse electromotive force generated by the inductive load is blocked at the load end of the Schottky diode and cannot reach the switching power supply.

[0013] Transient voltage suppression diode D2 is used to suppress the surge voltage transmitted to the output end of the switching power supply by the leakage current of the Schottky diode.

[0014] In a preferred embodiment of the present utility model, the DC-DC module includes a transformer chip U1, the transformer chip U1 input voltage positive terminal +Vin is connected to one end of the fuse element F1, and the other end of the fuse element F1 is connected to the DC power supply M48V; the transformer chip U1 input voltage positive terminal +Vin is also connected to one end of the capacitor C2 and one end of the capacitor C1, and the other end of the capacitor C1 and the other end of the capacitor C2 are both connected to the transformer chip U1 input voltage negative terminal -Vin; the transformer chip U1 input voltage negative terminal -Vin is connected to the power supply ground;

[0015] The positive terminal +Vo1 of the main output voltage of the transformer chip U1 and the positive output voltage sensing terminal +S of the transformer chip U1 are both connected to the positive electrode of the Schottky diode D1, the negative electrode of the Schottky diode D1 is connected to one end of the inductive load, and the other end of the inductive load is connected to the power ground terminal GND of the transformer chip U1;

[0016] The transformer chip U1 main output voltage positive terminal +Vo1 and the positive output voltage sensing terminal +S are also connected to one end of the capacitor C3 and the cathode of the transient voltage suppression diode D2. The other end of the capacitor C3 is connected to the transformer chip U1 negative output voltage sensing terminal -S and the power ground terminal GND. The other end of the capacitor C3 is also connected to the anode of the voltage suppression diode D2.

[0017] The cathode of the Schottky diode D1 is also connected to one end of the electrolytic capacitor C4, and the other end of the electrolytic capacitor C4 is connected to the anode of the transient voltage suppression diode D2.

[0018] Specifically, the 48V DC power supply is converted to 24V through the DC-DC module, and then supplies power to the DC brushed motor MOTO through the Schottky diode D1. The capacity of the electrolytic capacitor C4 is 470µF. Because the transient suppression diode D2 is not conducting, the Schottky diode D1 is in the forward conduction state, and the voltage drop is 0.6V, so the loss of the entire power supply path is very small.

[0019] When the inductive load starts and stops, due to the inductance of the inductive load itself, a reverse electromotive force pulse voltage is generated. This reverse electromotive force pulse voltage is superimposed on the 24V voltage, and the total voltage may even be as high as 2-5 times that of the 24V power supply. The reverse electromotive force pulse voltage propagates to the left in the direction of the DC-DC module, and charges the electrolytic capacitor C4 when passing through the electrolytic capacitor C4, and the reverse electromotive force pulse voltage is reduced. When the reverse electromotive force pulse voltage reaches the Schottky diode D1, since the voltage on the left side of the Schottky diode D1 is less than the voltage on the right side of the Schottky diode D1, the Schottky diode D1 does not conduct and is cut off. Most of the reverse electromotive force pulse voltage is blocked on the right side of the Schottky diode D1. Due to the reverse leakage current of the Schottky diode D1, a very small reverse electromotive force pulse voltage will leak to the left side of the Schottky diode D1. When the leakage reverse electromotive force pulse voltage at this time is greater than the starting conduction voltage of the transient suppression diode D2, the transient suppression diode D2 is turned on, and the voltage across the transient suppression diode D2 is limited to below 26.7V, which is safe for the DC-DC power supply module.

[0020] In a preferred implementation manner of the present utility model, the inductive load is one of a brushed motor, a brushless motor, a joint motor and a relay.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0022] 1. By utilizing the unidirectional conductivity of the pulse voltage suppression module, the switching power supply can normally output current to the inductive load, and the reverse electromotive force generated by the inductive load is blocked from reaching the switching power supply.

[0023] 2. The pulse voltage suppression module is used to suppress the weak surge voltage transmitted to the output end of the switching power supply by the leakage current generated by the pulse voltage suppression module.

[0024] 3. The reverse electromotive force absorption module is used to absorb part of the reverse electromotive force current, reduce the reverse electromotive force voltage, and reduce the reverse withstand voltage requirement of the reverse electromotive force isolation module.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 It is a work flow diagram of each module of the utility model;

[0028] Figure 2 It is a connection circuit relationship diagram of each module of the utility model. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] The utility model provides a circuit system for a switching power supply to drive an inductive load, comprising a switching power supply and an inductive load; further comprising a pulse voltage suppression module, a reverse electromotive force isolation module and a reverse electromotive force absorption module connected between the switching power supply and the inductive load; the switching power supply and the inductive load, the pulse voltage suppression module, the reverse electromotive force isolation module and the reverse electromotive force absorption module are connected in the same circuit.

[0031] like Figure 1 As shown, the specific working process of this embodiment is:

[0032] The forward current FV1 output by the switching power supply drives the inductive load to work through the pulse voltage suppression module.

[0033] The reverse electromotive force voltage RV1 generated by the inductive load at the moment of starting and stopping is reduced to RV2 after the reverse electromotive force absorption module absorbs part of the energy. After passing through the reverse electromotive force isolation module, most of it is isolated and blocked by the reverse electromotive force module and cannot pass through the reverse electromotive force isolation module. Since the reverse electromotive force isolation module is not an ideal isolation device, there will be reverse leakage current. Therefore, after passing through the reverse electromotive force isolation module, the reverse electromotive force voltage is reduced to RV3. After RV3 passes through the pulse voltage suppression module, the voltage above the threshold set by the pulse voltage suppression module will be clamped by the pulse voltage suppression module to the set safety threshold. Therefore, the reverse electromotive force voltage generated by the inductive load has been clamped in the safe voltage range, and this clamped safe voltage range does not harm the switching power supply.

[0034] In a preferred embodiment of the present invention, the switching power supply is a DC-DC module, and its model is LDFE75-48S24PS. In this embodiment, the DC-DC module is a small to medium power switching power supply.

[0035] In a preferred embodiment of the present invention, the pulse voltage suppression module is a transient voltage suppression diode D2, whose model is SMCJ24A; the reverse electromotive force isolation module is a Schottky diode D1; and the reverse electromotive force absorption module is an electrolytic capacitor C4.

[0036] In this embodiment, the pulse voltage suppression module can also be other voltage limiting devices or circuits, such as a varistor or a voltage stabilizing circuit; the reverse electromotive force isolation module can also be other unidirectional conductive devices, such as a rectifier diode.

[0037] like Figure 2 As shown, in a preferred embodiment of the utility model, the DC-DC module includes a transformer chip U1, the transformer chip U1 input voltage positive terminal +Vin is connected to the fuse element F1, and the other end of the fuse element F1 is connected to the DC power supply; the transformer chip U1 input voltage positive terminal +Vin is also connected to one end of the capacitor C2 and one end of the capacitor C1, and the other ends of the capacitor C1 and the capacitor C2 are both connected to the transformer chip U1 input voltage negative terminal -Vin; the transformer chip U1 input voltage negative terminal -Vin is connected to the power supply ground;

[0038] The positive terminal +Vo1 of the main output voltage of the transformer chip U1 and the positive output voltage sensing terminal +S are both connected to the positive electrode of the Schottky diode D1, the negative electrode of the Schottky diode D1 is connected to one end of the inductive load, and the other end of the inductive load is connected.

[0039] The transformer chip U1 main output voltage positive terminal +Vo1 and the positive output voltage sensing terminal +S are also connected to one end of the capacitor C3 and the cathode of the transient voltage suppression diode D2. The other end of the capacitor C3 is connected to the transformer chip U1 negative output voltage sensing terminal -S and the power ground terminal GND. The other end of the capacitor C3 is also connected to the anode of the voltage suppression diode D2.

[0040] The cathode of the Schottky diode D1 is also connected to one end of the electrolytic capacitor C4, and the other end of the electrolytic capacitor C4 is connected to the anode of the transient voltage suppression diode D2.

[0041] In a preferred implementation manner of the present utility model, the inductive load is one of a brushed motor, a brushless motor, a joint motor and a relay.

[0042] The inductive load in this embodiment is a brushed DC motor MOTO.

[0043] The working principle of the utility model is:

[0044] The 48V DC power supply is converted to 24V through the DC-DC module U1, and then supplies power to the DC brushed motor MOTO through the Schottky diode D1. The capacity of the electrolytic capacitor C4 is 470µF, because the transient suppression diode D2 is not conducting. The Schottky diode D1 is in the forward conduction state, and the voltage drop is 0.6V, so the loss of the entire power supply path is very small.

[0045] When the inductive load starts and stops, due to the inductance of the inductive load itself, a reverse electromotive force pulse voltage is generated. This reverse electromotive force pulse voltage is superimposed on the 24V voltage, and the total voltage may even be as high as 2-5 times of the 24V power supply. The reverse electromotive force pulse voltage propagates to the left to the DC-DC module U1, and charges the electrolytic capacitor C4 when passing through the electrolytic capacitor C4. The capacity of the electrolytic capacitor C4 is 470µF, and the reverse electromotive force pulse voltage is reduced. When the reverse electromotive force pulse voltage reaches the Schottky diode D1, the voltage on the left side of the Schottky diode D1 is less than the voltage on the right side of the Schottky diode D1. The Schottky diode D1 is not turned on and is cut off. Most of the reverse electromotive force pulse voltage is blocked on the right side of the Schottky diode D1. Due to the reverse leakage current of the Schottky diode D1, a very small reverse electromotive force pulse voltage will leak to the left side of the Schottky diode D1. When the leakage reverse electromotive force pulse voltage at this time is greater than the starting conduction voltage of the transient suppression diode D2, the transient suppression diode D2 is turned on, and the voltage across the transient suppression diode D2 is limited to below 26.7V, which is safe for the DC-DC power supply module.

[0046] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A circuit system for driving an inductive load with a switching power supply, comprising a switching power supply and an inductive load; characterized in that: The output end of the switching power supply is connected to one end of the pulse voltage suppression module and one end of the reverse electromotive force isolation module, the other end of the pulse voltage suppression module is connected to the inductive load and one end of the reverse electromotive force absorption module, the other end of the inductive load is connected to the other end of the reverse electromotive force absorption module and the other end of the reverse electromotive force isolation module in turn, and the other end of the reverse electromotive force isolation module is connected to the power ground of the switching power supply.

2. The circuit system for driving an inductive load with a switching power supply as claimed in claim 1, wherein: The switching power supply is a DC-DC module, and its model is LDFE75-48S24PS.

3. The circuit system for driving an inductive load with a switching power supply as claimed in claim 2, wherein: The pulse voltage suppression module is a transient voltage suppression diode D2, whose model is SMCJ24A; the reverse electromotive force isolation module is a Schottky diode D1; and the reverse electromotive force absorption module is an electrolytic capacitor C4.

4. The circuit system for driving an inductive load with a switching power supply as claimed in claim 3, wherein: The DC-DC module includes a transformer chip U1, the transformer chip U1 input voltage positive terminal +Vin is connected to one end of the fuse element F1, and the other end of the fuse element F1 is connected to the DC power supply M48V; the transformer chip U1 input voltage positive terminal +Vin is also connected to one end of the capacitor C2 and one end of the capacitor C1, and the other end of the capacitor C1 and the other end of the capacitor C2 are both connected to the transformer chip U1 input voltage negative terminal -Vin; the transformer chip U1 input voltage negative terminal -Vin is connected to the power supply ground; The positive terminal +Vo1 of the main output voltage of the transformer chip U1 and the positive output voltage sensing terminal +S of the transformer chip U1 are both connected to the positive electrode of the Schottky diode D1, the negative electrode of the Schottky diode D1 is connected to one end of the inductive load, and the other end of the inductive load is connected to the power ground terminal GND of the transformer chip U1; The transformer chip U1 main output voltage positive terminal +Vo1 and the transformer chip U1 positive output voltage sensing terminal +S are also connected to one end of the capacitor C3 and the cathode of the transient voltage suppression diode D2. The other end of the capacitor C3 is connected to the transformer chip U1 negative output voltage sensing terminal -S and the transformer chip U1 power ground terminal GND. The other end of the capacitor C3 is also connected to the anode of the voltage suppression diode D2. The cathode of the Schottky diode D1 is also connected to one end of the electrolytic capacitor C4, and the other end of the electrolytic capacitor C4 is connected to the anode of the transient voltage suppression diode D2.

5. The circuit system for driving an inductive load with a switching power supply as claimed in claim 1, wherein: The inductive load is one of a brushed motor, a brushless motor, a joint motor and a relay.

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