Driver soft start and protection circuit based on series double relay control

Abstract

The utility model discloses a driver soft start and protection circuit based on series double-relay control, and relates to the field of driver soft start circuits. Comprising driver input power electricity, the two ends of the driver input power electricity are connected with a bus capacitor C1 in parallel through a direct current bus, a relay K1 and a relay K2 are connected between the driver input power electricity and the bus capacitor C1 in series, and coils of the relay K1 and the relay K2 are correspondingly connected with relay control circuits respectively; the two ends of the relay K2 are connected with a current-limiting resistor R1 in parallel, a direct-current bus voltage detection module is further connected between the positive electrode and the negative electrode of input power electricity of the driver, and the direct-current bus voltage detection module is connected with the relay K1 and a relay control circuit corresponding to the relay K2 through a control system; when a system controller or a driver breaks down, the relay K1 can be controlled to be switched off actively, and the function of fault rapid isolation is achieved.

Description

Technical Field

[0001] This utility model relates to the field of driver soft-start circuits, specifically a driver soft-start and protection circuit based on series dual relay control. Background Technology

[0002] Because the DC bus circuit of the driver contains a large capacitor, applying voltage instantaneously will generate a large inrush current. This inrush current may cause system instability and, in severe cases, damage components. Therefore, the driver typically pre-charges the DC bus capacitor through a current-limiting resistor when the power is turned on. After pre-charging, the current-limiting resistor is short-circuited through a relay. This process limits the instantaneous inrush current, and such a circuit is called a driver soft-start circuit. Soft-start circuits have the following advantages: low starting current; regardless of whether the load is large or capacitive, only a small starting current is generated, effectively improving the stability of system operation.

[0003] The existing technology has the following drawbacks: if the system is powered off and then powered on again momentarily, the driver bus still stores a high voltage. If the soft-start relay contacts do not reach the voltage threshold for disconnection, they will remain in the energized state and thus lose the function of power-on soft start. Utility Model Content

[0004] The purpose of this invention is to provide a driver soft-start and protection circuit based on series dual relay control. Compared with commonly used soft-start circuits, it has the advantage of protecting against soft-start abnormalities (such as the soft-start relay being in the energized state before power-on), and also has the function of disconnecting the power supply to achieve fault isolation between devices when other faults occur in the system.

[0005] The technical solution to achieve the above objective is: a driver soft start and protection circuit based on series dual relay control, characterized in that: it includes driver input power, the two ends of the driver input power are connected in parallel with a bus capacitor C1 through a DC bus, and relays K1 and K2 are connected in series between the driver input power and the bus capacitor, and the coils of relays K1 and K2 are respectively connected to relay control circuits.

[0006] A current-limiting resistor R1 is connected in parallel across the two ends of relay K2. A DC bus voltage detection module is also connected between the positive and negative terminals of the driver input power. The DC bus voltage detection module is connected to the relay control circuits corresponding to relay K1 and relay K2 through the control system.

[0007] The DC bus voltage detection module is used to detect the bus voltage, and the control system is used to control the opening and closing of relays K1 and K2 according to the bus voltage magnitude.

[0008] Furthermore, the DC bus voltage detection module includes resistors R2 and R3 and a voltage sampling circuit. One end of R2 is connected to the positive terminal V+ of the driver input power, and the other end is connected to one end of resistor R3. The other end of resistor R3 is connected to the negative terminal V- of the driver input power. The signal input terminal of the voltage sampling circuit is connected to the connection point between resistors R2 and R3 and the negative terminal V- of the driver input power, respectively.

[0009] Furthermore, the control system includes a driver CPU, a CAN communication circuit, and a system controller. The signal input terminal of the driver CPU is connected to the system controller through the CAN communication circuit, and the I / O ports of the driver CPU are respectively connected to the relay control circuits corresponding to relays K1 and K2.

[0010] The beneficial effects of this utility model are as follows: When the driver bus voltage has not completed self-discharge (driver bus undervoltage), the system is powered on again. The driver CPU output I / O port can determine whether relay K2 is in the off state, ensuring that the system can achieve soft start every time it is powered on. This avoids the system directly energizing the bus capacitor when relay K2 is still in the energized state, causing power supply output protection, or even damage to components in the equipment.

[0011] When the system controller or driver fails, the relay K1 can be actively disconnected by the driver CPU command, thus achieving the function of rapid fault isolation. Attached Figure Description

[0012] Figure 1 This is a block diagram of the driver soft-start and protection circuit based on series dual relay control of this utility model. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1 As shown, this utility model discloses a driver soft start and protection circuit based on series dual relay control, including driver input power, the two ends of the driver input power are connected in parallel with a bus capacitor C1 through a DC bus, and relays K1 and K2 are connected in series between the driver input power and the bus capacitor C1, and the coils of relays K1 and K2 are respectively connected to relay control circuits.

[0015] A current-limiting resistor R1 is connected in parallel across the two ends of relay K2. Before relay K2 is energized, the bus capacitor C1 is pre-charged through the current-limiting resistor R1.

[0016] A DC bus voltage detection module 1 is also connected between the positive and negative terminals of the driver input power. The DC bus voltage detection module 1 is connected to the relay control circuit 3 corresponding to relays K1 and K2 through the control system. The DC bus voltage detection module 1 includes resistors R2 and R3 and a voltage sampling circuit 2. One end of R2 is connected to the positive terminal V+ of the driver input power, and the other end is connected to one end of resistor R3. The other end of resistor R3 is connected to the negative terminal V- of the driver input power. The signal input terminal of the voltage sampling circuit 2 is connected to the connection point between resistors R2 and R3 and the negative terminal V- of the driver input power, respectively.

[0017] The control system includes a driver CPU4, a CAN communication circuit 5, and a system controller 6 (specifically, the controller of the driver control system). The signal input terminal of the driver CPU4 is connected to the system controller 6 through the CAN communication circuit 5. The I / O ports of the CPU of the driver CPU4 are respectively connected to the relay control circuits 3 corresponding to relays K1 and K2.

[0018] The principle of this utility model is:

[0019] Based on the original relay K2 in the general soft-start circuit, a relay K1 is added. When the system powers on the driver, it first sends the power-on signal to the driver CPU4 through the CAN communication circuit 5. The driver CPU4 reads the bus voltage value through the DC bus voltage detection module 1 and reads the output I / O port status to confirm that the relay K2 is in the off state. If the relay K2 is detected to be in the energized state, the corresponding relay control circuit 3 is used to turn off the relay K2 first, and then the system responds to the power-on command to the driver and the corresponding relay control circuit 3 is used to energize the relay K1.

[0020] Then, the DC bus capacitor C1 is precharged through the current-limiting resistor R1. The DC bus voltage detection module 1 monitors the bus voltage value in real time. Once the precharging is completed, the control relay K2 is activated to short-circuit the current-limiting resistor R1, and the driver is powered on and soft-started.

[0021] After the system is powered off, relay K1 is disconnected. Since the bus capacitor C1 still stores a certain amount of energy, the bus voltage value drops slowly. The DC bus voltage detection module 1 monitors the bus voltage value in real time. When it detects that the bus voltage is lower than the bus undervoltage value, it turns off relay K2. If the system applies power to the driver again when relay K2 is not disconnected, the power-on soft start function can continue to be realized according to the above working principle.

[0022] When the system controller 6 or the driver malfunctions, the driver CPU4 controls the relay K1 to disconnect, which can quickly disconnect the power supply and thus isolate the fault.

[0023] In summary, this utility model, based on a driver soft-start and protection circuit controlled by a series dual relay, can prevent secondary power application from damaging the equipment. The circuit is simple and easy to implement, and it has the function of quickly isolating the fault by disconnecting the power supply when the system malfunctions.

[0024] The above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Any person skilled in the art may use the above-disclosed technical content to make changes or modifications to the equivalent embodiments and apply them to other fields. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of this utility model without departing from the content of the technical solution of this utility model shall still fall within the protection scope of the technical solution of this utility model.

Claims

1. A soft start and protection circuit for a driver based on series double relay control, characterized in that: The drive input power is connected with the bus capacitor C1 in parallel through a DC bus, and a relay K1 and a relay K2 are connected in series between the drive input power and the bus capacitor C1, and the coils of the relay K1 and the relay K2 are respectively connected with a relay control circuit; The relay K2 is connected with a current-limiting resistor R1 in parallel, and a DC bus voltage detection module is further connected between the positive and negative poles of the drive input power, and the DC bus voltage detection module is connected with the relay control circuits of the relay K1 and the relay K2 through a control system; The DC bus voltage detection module is used for detecting the bus voltage, and the control system is used for controlling the turn-on and turn-off of the relay K1 and the relay K2 according to the bus voltage.

2. The soft starter and protection circuit for a drive controlled by series double breakers of claim 1, wherein: The DC bus voltage detection module comprises resistors R2 and R3 and a voltage sampling circuit, one end of the resistor R2 is connected with the positive pole V+ of the drive input power, the other end of the resistor R2 is connected with one end of the resistor R3, the other end of the resistor R3 is connected with the negative pole V- of the drive input power, and the signal input ends of the voltage sampling circuit are respectively connected with the connection point between the resistors R2 and R3 and the negative pole V- of the drive input power.

3. The drive soft start and protection circuit based on series double-relay control of claim 1, wherein: The control system comprises a drive CPU, a CAN communication circuit and a system controller, the signal input end of the drive CPU is connected with the system controller through the CAN communication circuit, and the I / O port of the CPU of the drive CPU is respectively connected with the relay control circuits of the relay K1 and the relay K2.

Images