Power supply equipment relay driving circuit and control method thereof

Abstract

The invention discloses a power supply equipment relay driving circuit and a control method thereof, and belongs to the technical field of power supply equipment. A change-over switch comprises a first branch and a second branch of which the output ends are intersected; a coil of the first relay unit, the first branch, a coil of the second relay unit and a contact side of the second switch are connected in series to two ends of the power supply; the second branch, the coil of the second relay unit and the contact side of the second switch are connected in series to two ends of the power supply; a coil of the first relay unit and a contact side of the first switch are connected in series to two ends of the power supply; the common end of the coil of the first relay unit and the contact side of the first switch is connected to the control end of the change-over switch, so that the first branch circuit and the second branch circuit are driven to be switched on and off, and coil current path switching of the first relay unit and the second relay unit is achieved. The control method comprises three working modes. According to the invention, power consumption after actuation of the relay can be effectively reduced and electromagnetic interference can be reduced.

Description

Technical Field

[0001] This invention relates to the field of power supply equipment technology, and in particular to a relay drive circuit for power supply equipment and its control method. Background Technology

[0002] Relays are automatic switching components with isolation functions and are key safety components in power supply equipment. They are widely used in the field of new energy vehicles. Power supply equipment usually uses two or more relays. Relays control the switching of high voltage through low voltage. A higher voltage is required when the relay is energized. After the relay is energized, it usually needs 30% to 80% of the voltage to keep the contacts closed. Some relays explicitly require that they should not be used for a long time without reducing the driving voltage after the contacts are energized, in order to prevent the coil from overheating and reducing the service life of the relay.

[0003] Currently, due to safety requirements, electric vehicle power supply equipment needs to reduce coil power consumption after the relay is activated. Common sampling methods include:

[0004] 1. The relay is controlled by two transistors. One transistor controls the relay to be energized, and the other transistor controls the relay coil to be energized by voltage division through a series resistor, thereby reducing the heat of the relay coil. This solution transfers the heat of the relay coil to the resistor.

[0005] 2. The relay is controlled by the main power supply, the auxiliary power supply, and two transistors. One transistor controls the main power supply to provide the rated voltage to make the relay energize, and the other transistor controls the auxiliary power supply to provide the holding voltage to keep the relay energized, thereby reducing the heat of the relay coil. The auxiliary power supply used in this scheme requires a buck circuit to reduce power consumption. Its circuit cost is high, the output voltage is fixed, and the high-frequency operation of the circuit will generate a large amount of electromagnetic interference.

[0006] 3. Relays reduce the relay coil current, and transistors control the relay to engage. PWM control is also used to reduce the relay coil current, thereby reducing the heat generated by the relay coil. However, this method increases switching power loss and causes severe electromagnetic interference due to transistor PWM control. Using multiple relays will multiply the switching power loss and electromagnetic interference.

[0007] The aforementioned power supply equipment reduces coil power consumption after the relay is engaged. Option 1 reduces coil heat by lowering the relay voltage through resistor voltage division, but requires an additional control circuit and generates extra power consumption due to the resistor. Option 2 reduces coil heat by lowering the relay voltage through dual power supplies, but requires an additional control circuit and an auxiliary buck circuit, resulting in high cost, fixed voltage, and significant electromagnetic interference. Option 3 reduces coil heat by lowering the relay current through PWM control, but this leads to transistor switching power loss and severe electromagnetic interference; using multiple relays exponentially increases switching power loss and electromagnetic interference. Therefore, it is necessary to design a power supply equipment relay drive circuit and its control method that is simple in circuitry, flexible in use, low in power consumption, and has minimal electromagnetic interference, thereby reducing costs and improving practicality. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a relay drive circuit for power supply equipment and its control method, which solves the technical problems of the three existing solutions provided in the background art.

[0009] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0010] In a first aspect, the present invention provides a relay drive circuit for a power supply device, including a power supply, a first relay unit, a first switch, a second relay unit, a second switch, and a switching switch, wherein the switching switch includes a first branch and a second branch whose output terminals intersect.

[0011] The coil of the first relay unit, the first branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply.

[0012] The second branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply.

[0013] The coil of the first relay unit and the contact side of the first switch are connected in series across the two ends of the power supply.

[0014] The common terminal of the coil of the first relay unit and the contact side of the first switch is connected to the control terminal of the switching switch, thereby driving the opening and closing of the first branch and the second branch, realizing the switching of the coil current path of the first relay unit and the second relay unit.

[0015] Optionally, the first relay unit or the second relay unit consists of a single relay or multiple relays connected in parallel, and each relay coil has a protection device connected in parallel, wherein the protection device is a diode or a series combination of a diode and a resistor.

[0016] Optionally, both the first switch and the second switch include transistors. The control terminal of the transistor in the first switch is connected to a first control signal source, and the two contacts on the contact side are respectively connected to the ground wire and the coil of the first relay unit. The control terminal of the transistor in the second switch is connected to a second control signal source, and the two contacts on the contact side are respectively connected to the ground wire and the coil of the second relay unit.

[0017] Optionally, both the first switch and the second switch include a current-limiting resistor and a pull-down resistor. The current-limiting resistor is connected to the control terminal of the transistor, and the control terminal of the transistor is grounded through the pull-down resistor.

[0018] Optionally, the switching switch includes a transistor, a Zener diode, a resistor, and a diode. The diode forms a first branch connected between the coils of the first relay unit and the second relay unit. The two contacts on the contact side of the transistor form a second branch, which are respectively connected to the power supply and the coil of the second relay unit. The common terminal of the diode and the coil of the first relay unit is connected to the control terminal of the transistor via the Zener diode and the resistor.

[0019] In a second aspect, the present invention provides a power supply device, including the power supply device relay drive circuit as described above.

[0020] Thirdly, the present invention provides a control method applicable to the above-mentioned power supply equipment relay drive circuit, comprising:

[0021] The drive starts, controlling the first and second switches to conduct;

[0022] The driving process includes:

[0023] Mode 1: Control the first switch to turn off to achieve voltage switching;

[0024] Mode 2 uses a PWM control signal to excite the first switch to turn on and off, achieving a hybrid drive of voltage switching and PWM injection current.

[0025] Mode 3: Control the first switch to turn off, and use the PWM control signal to excite the second switch to turn on and off, thereby realizing voltage switching and PWM current reduction hybrid drive;

[0026] When the drive ends, the first and second switches are turned off.

[0027] Optionally, the three modes can be freely switched.

[0028] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0029] The power supply equipment relay drive circuit provided by this invention can control the on and off of two or more relays without the need for additional control circuits, voltage divider resistors, or auxiliary power supplies. This circuit has a simple structure, is flexible in use, has low power consumption, small size, and minimal electromagnetic interference, thus offering cost advantages and high practicality.

[0030] The power supply equipment relay drive circuit controls the first and second switches to turn on and off respectively through the first and second control signals. This can achieve delayed closing between the first and second relays, avoid the superposition of surge currents and simultaneous arcing of relay contacts, and improve the life of the relays.

[0031] The control method for the relay drive circuit of the power supply equipment provided by this invention includes three operating modes. Mode 1 keeps the first and second relays engaged by turning off the first switch and turning on the second switch, without generating additional power consumption or electromagnetic interference. Mode 2 keeps the first and second relays engaged by using PWM to excite the first switch to turn on and off, and controlling the switching path selection and turning on the second switch, resulting in greater holding force and less electromagnetic interference. Mode 3 keeps the first and second relays engaged by turning off the first switch and using a second control signal to excite the second switch to turn on and off via PWM, achieving even lower power consumption and less electromagnetic interference. Attached Figure Description

[0032] Figure 1 This is a structural block diagram of the power supply equipment relay drive circuit provided in an embodiment of the present invention;

[0033] Figure 2 This is a specific topology diagram of the relay drive circuit for power supply equipment provided in an embodiment of the present invention;

[0034] Figure 3 This is a flowchart of the control method for the relay drive circuit of the power supply equipment provided in the embodiment of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1As shown, this embodiment of the invention provides a relay driving circuit for a power supply device, including a power supply, a first relay unit, a first switch, a second relay unit, a second switch, and a switching switch. The switching switch includes a first branch and a second branch whose output terminals intersect. The coil of the first relay unit, the first branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply. The second branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply. The coil of the first relay unit and the contact side of the first switch are connected in series across the two ends of the power supply. The common terminal of the coil of the first relay unit and the contact side of the first switch is connected to the control terminal of the switching switch, thereby driving the switching of the first branch and the second branch, realizing the switching of the coil current path of the first relay unit and the second relay unit.

[0038] Specifically, in this embodiment, the first relay unit or the second relay unit consists of a single relay or multiple relays connected in parallel. Each relay coil has a protection device connected in parallel, and the protection device is a diode or a series combination of a diode and a resistor. For example... Figure 2 As shown, this embodiment uses only a single relay as an example. The coils of the first relay unit and the second relay unit are denoted as K1 and K2, respectively. Both coils K1 and K2 are connected in parallel with protection devices. The protection devices are diodes or a series combination of diodes and resistors. The diodes are used to absorb the coil spike voltage when the relay is turned off. When the relay is controlled by PWM, the current is maintained. In this embodiment, only diodes are used as protection devices, denoted as D1 and D2, respectively.

[0039] Both the first switch and the second switch include transistors. In this embodiment, MOSFET transistors are used, denoted as Q1 and Q2 respectively. The control terminal (i.e., gate) of transistor Q1 is connected to the first control signal source Relay1_CTRL, and the two contacts on the contact side (i.e., source and drain) are respectively connected to the ground and the coil K1 of the first relay unit. The control terminal of transistor Q2 is connected to the second control signal source Relay2_CTRL, and the two contacts on the contact side are respectively connected to the ground and the coil K2 of the second relay unit.

[0040] Both the first and second switches include current-limiting resistors and pull-down resistors. The current-limiting resistors and pull-down resistors of the first switch are denoted as R1 and R2, and the current-limiting resistors and pull-down resistors of the second switch are denoted as R3 and R4. The current-limiting resistors are connected to the control terminal of the transistor and can suppress oscillations and limit instantaneous inrush currents. The control terminal of the transistor is grounded through the pull-down resistors to ensure a definite state and prevent false triggering.

[0041] The switching device includes a transistor, a Zener diode, a resistor, and a diode, denoted as Q3, ZD1, R5, and D3, respectively. Diode D3 forms the first branch, which is connected between the coils (K1 and K2) of the first and second relay units. Transistor Q3 is a bipolar transistor. The two contacts (i.e., emitter and collector) on the contact side of transistor Q3 are connected to the power supply VCC and the coil K2 of the second relay unit, respectively. The common terminal of diode D3 and the coil K1 of the first relay unit is connected to the control terminal (i.e., base) of transistor Q3 through Zener diode ZD1 and resistor R5.

[0042] Resistor R5 is connected to the control terminal of transistor Q3. To ensure the stability of the entire drive circuit, transistor Q3 needs to operate in either the off or on state, and the voltage across Zener diode ZD1 is 0.5V. ~ Between, according to the transistor amplification factor Power supply voltage Voltage of Zener diode ZD1 during operation The junction voltage of transistor Q3 and the relay rated current The maximum value of R5 can be calculated using the formula below:

[0043]

[0044] Specifically, in this embodiment, the first control signal source Relay1_CTRL and the second control signal source Relay2_CTRL are level or PWM signals, with a high level of +3.3V or 5V and a low level of 0V. The PWM frequency is preferably 10kHz~30Hz, and the PWM duty cycle is adjustable from 0 to 100%.

[0045] When the first switch is on, transistor Q3 is on while diode D3 is off, and the power supply voltage for relay K2 is VCC; when the first switch is off, transistor Q3 is off while diode D3 is off and on, and the power supply voltage for relay K2 is the voltage after the voltage is divided by relay K1.

[0046] The power supply equipment relay drive circuit provided in this embodiment has a simple structure, flexible use, low power consumption, small size, and minimal electromagnetic interference, resulting in cost advantages and high practicality. By outputting level or PWM signals from the first and second control signal sources, the first and second switches are controlled. The switching switches select the current path for the first and second relay units based on the on / off state of the first switch, enabling various control methods such as low power consumption, low electromagnetic interference, and enhanced holding force. Simultaneously, by controlling the on and off of the first and second switches respectively through the first and second control signal sources, delayed closing between the first and second relays can be achieved, avoiding surge current superposition and simultaneous arcing of relay contacts, thus improving relay lifespan.

[0047] Example 2

[0048] like Figure 3 As shown, this embodiment of the invention provides a control method applicable to the above-described relay drive circuit of a power supply device, comprising:

[0049] (1) Drive starts, control the first switch and the second switch to be turned on.

[0050] The first switch is turned on, driving the first relay unit to close. The coil of the first relay unit and the first switch form the first circuit. At the same time, the input terminal of the switching switch is connected to the power supply.

[0051] When the second switch is turned on, it drives the second relay unit to close, and the coil of the second relay unit and the second switch form a second circuit.

[0052] (2) The driving process includes:

[0053] (2.1) Mode 1: Control the first switch to turn off to achieve voltage switching.

[0054] When the first switch is turned off, the input terminal of the switching switch is connected to the coil of the first relay unit (the first branch is turned on), and the coil of the first relay unit, the coil of the second relay unit, and the second switch form a circuit.

[0055] Mode 1 reduces power consumption by lowering the voltage on the relay coil without generating additional power consumption or electromagnetic interference.

[0056] (2.2) Mode 2: The first switch is turned on and off by PWM control signal to realize voltage switching and PWM injection current mixed drive.

[0057] When the first switch is turned on, the running state is consistent with the running state at the start of the drive; when the first switch is turned off, the running state is consistent with the running state in mode one.

[0058] Mode 2 reduces power consumption by decreasing the current in the relay coil. Since the second switch remains on, there is a continuous current in the first and second relays, thus reducing the switching power loss of the first switch, minimizing electromagnetic interference, and enabling the relay to achieve a greater holding force.

[0059] (2.3) Mode 3: Control the first switch to turn off, and excite the second switch to turn on and off through the PWM control signal to realize voltage switching and PWM current reduction hybrid drive.

[0060] When the first switch is turned off, the input terminal of the switching switch is connected to the coil of the first relay unit. The coil of the first relay unit, the coil of the second relay unit, and the second switch form a circuit.

[0061] When the second switch is turned on, the operating state is the same as in mode one; when the second switch is turned off, the operating state is the same as when the drive ends.

[0062] Mode 3 significantly reduces power consumption by lowering the current and voltage on the relay coil. Furthermore, since the first switch is turned off, the current and voltage of the first and second relays are reduced, thus reducing the switching power loss of the second switch and minimizing electromagnetic interference, further reducing power consumption.

[0063] You can freely switch between Mode 1, Mode 2 and Mode 3.

[0064] (3) When the drive ends, control the first switch and the second switch to turn off.

[0065] When the first and second switches are turned off, the first and second relay units are turned off.

[0066] The control method provided in this embodiment enables the high-voltage side of the first and second relays to be turned on and off through the first and second control signal sources. After the high-voltage side of the relay is fully engaged, the power consumption of the relay can be reduced by changing the level of the first and second control signals or by PWM excitation. The power consumption reduction and the impact of electromagnetic interference can be achieved by reducing the holding voltage, reducing the holding current, and reducing both the holding voltage and current.

[0067] Example 3

[0068] This invention provides a power supply device, including the power supply device relay drive circuit as described in Embodiment 1 above.

[0069] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0070] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0071] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0072] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A relay drive circuit for a power supply device, characterized in that, It includes a power supply, a first relay unit, a first switch, a second relay unit, a second switch, and a switching switch, wherein the switching switch includes a first branch and a second branch whose output terminals intersect. The coil of the first relay unit, the first branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply. The second branch, the coil of the second relay unit, and the contact side of the second switch are connected in series across the two ends of the power supply. The coil of the first relay unit and the contact side of the first switch are connected in series across the two ends of the power supply. The common terminal of the coil of the first relay unit and the contact side of the first switch is connected to the control terminal of the switching switch, thereby driving the opening and closing of the first branch and the second branch, realizing the switching of the coil current path of the first relay unit and the second relay unit.

2. The power supply equipment relay drive circuit according to claim 1, characterized in that, The first relay unit or the second relay unit consists of a single relay or multiple relays connected in parallel. Each relay coil has a protection device connected in parallel, and the protection device is a diode or a series combination of a diode and a resistor.

3. The power supply equipment relay drive circuit according to claim 1, characterized in that, Both the first switch and the second switch include transistors. The control terminal of the transistor in the first switch is connected to a first control signal source, and the two contacts on the contact side are respectively connected to the ground wire and the coil of the first relay unit. The control terminal of the transistor in the second switch is connected to a second control signal source, and the two contacts on the contact side are respectively connected to the ground wire and the coil of the second relay unit.

4. The power supply equipment relay drive circuit according to claim 3, characterized in that, Both the first switch and the second switch include a current-limiting resistor and a pull-down resistor. The current-limiting resistor is connected to the control terminal of the transistor, and the control terminal of the transistor is grounded through the pull-down resistor.

5. The power supply equipment relay drive circuit according to claim 1, characterized in that, The switching switch includes a transistor, a Zener diode, a resistor, and a diode. The diode forms a first branch connected between the coils of the first relay unit and the second relay unit. The two contacts on the contact side of the transistor form a second branch, which are respectively connected to the power supply and the coil of the second relay unit. The common terminal of the diode and the coil of the first relay unit is connected to the control terminal of the transistor via the Zener diode and the resistor.

6. A power supply device, characterized in that, Includes the power supply equipment relay drive circuit as described in any one of claims 1-5.

7. A control method applicable to the relay drive circuit of the power supply equipment according to any one of claims 1-5, characterized in that, include: The drive starts, controlling the first and second switches to conduct; The driving process includes: Mode 1: Control the first switch to turn off to achieve voltage switching; Mode 2 uses a PWM control signal to excite the first switch to turn on and off, achieving a hybrid drive of voltage switching and PWM injection current. Mode 3: Control the first switch to turn off, and use the PWM control signal to excite the second switch to turn on and off, thereby realizing voltage switching and PWM current reduction hybrid drive; When the drive ends, the first and second switches are turned off.

8. The control method for the relay drive circuit of the power supply equipment according to claim 7, characterized in that, The user can freely switch between Mode 1, Mode 2, and Mode 3.

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