Relay energy-saving driving control circuit

Abstract

The invention relates to a relay energy-saving driving control circuit, and the circuit comprises a first power converter of which the input end is connected with the positive end of an input power supply, and which is used for carrying out the voltage conversion of an input power supply voltage to obtain a conversion voltage; the first end of the feedback resistor is connected to the negative electrode end of the input power supply, the second end of the feedback resistor is connected to the output end of the first power converter, and the resistance value of the feedback resistor is adjustable and used for adjusting the conversion voltage to obtain relay driving output voltage. The output feedback resistance of the power converter is controlled and adjusted by the switch to adjust the output voltage of the power converter, so that higher voltage is output when the relay is started, and lower voltage is output when the relay is kept, so that the power consumption is reduced, the temperature rise is reduced, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of relay control circuits, and in particular to a relay energy-saving drive control circuit. Background Art

[0002] Relays can be used to control larger load power with smaller control power, and the relay drive control and load contacts are isolated, so they are widely used in various electrical control fields. Generally, for the drive control of the relay, a higher drive power is usually required in the short time of starting the relay, while only a smaller drive power is required during the relay holding stage.

[0003] In the prior art, the main method for driving the relay is to drive it with a constant voltage. The disadvantage of this driving control method is that even if the relay is in the holding stage, its power consumption is still large, the temperature rise is high, resulting in power waste, relay aging, and shortened service life. In addition, PWM driving control with a single driving power supply and power switching control with two driving power supplies can also be used to perform energy-saving control, but these driving control implementation methods are complex and costly.

[0004] Therefore, it is necessary to improve the existing relay drive control scheme in order to achieve low cost and simple implementation method under energy-saving control. Summary of the invention

[0005] In view of this, it is necessary to provide a relay energy-saving drive control circuit, which uses switch control to adjust the output feedback resistance of the power converter to adjust and change the output voltage of the power converter, so that when the relay is started, a higher voltage is output so that the relay can quickly achieve state transition; and at other times including the relay holding stage, the power converter outputs a lower voltage to reduce the power consumption of the relay and the control system, reduce the temperature rise, and extend the service life.

[0006] In order to achieve the above object, the present invention provides a relay energy-saving drive control circuit, comprising: A first power converter, whose input terminal is connected to the positive terminal of the input power supply, and is used to convert the input power supply voltage to obtain a conversion voltage; A feedback resistor, a first end of which is connected to the negative terminal of the input power supply, and a second end of which is connected to the output terminal of the first power converter, wherein the resistance of the feedback resistor is adjustable and is used to adjust the conversion voltage to obtain the relay drive output voltage.

[0007] In a possible implementation, the feedback resistor includes a first resistor and a second resistor, the first end of the first resistor is connected to the output end of the first power converter, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the output end of the first power converter; wherein at least one of the first resistor and the second resistor has an adjustable resistance.

[0008] In a possible implementation, the calculation formula of the relay drive output voltage is: ; in, is the relay drive output voltage, VFB is the internal reference power supply voltage of the first power converter, R1 is the first resistor, R2 is the second resistor.

[0009] In a possible implementation, the feedback resistor further includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; the control circuit further includes a first control switch, two ends of the first control switch are respectively connected to one end of the second resistor and one end of the third resistor; The resistance value of the feedback resistor is changed by changing the opening and closing state of the first control switch.

[0010] In a possible implementation, the calculation formula of the relay drive output voltage is: ; in, is the relay drive output voltage, VFB is the internal reference power supply voltage of the first power converter, R1 is the first resistor, R2 is the second resistor, R3 is the third resistor.

[0011] In a possible implementation, the feedback resistor further includes a third resistor, and a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit further includes a second power converter, a control unit, a MOS tube, a fourth resistor and a fifth resistor; the input end of the second power converter is connected to the output end of the first power converter, the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the fourth resistor; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube, the second end of the fifth resistor is connected to the source of the MOS tube and the second end of the second resistor; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a first control signal, and the first control signal is used to control the on-off state of the MOS tube to adjust the relay drive output voltage.

[0012] In a possible implementation, the feedback resistor further includes a third resistor, and a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit also includes a second power converter, a control unit, a MOS tube, a first capacitor, a first diode, a fourth resistor, a fifth resistor and a sixth resistor; the input end of the second power converter is connected to the output end of the first power converter, and the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the sixth resistor and the first end of the first capacitor; the second end of the sixth resistor is connected to the positive end of the first diode; the second end of the first capacitor is connected to the first end of the fourth resistor and the negative end of the first diode; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube; the second end of the fifth resistor is connected to the source of the MOS tube, the second end of the second resistor and the positive end of the first diode; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a second control signal, and the second control signal is used to control the on / off state and delay state of the MOS tube to adjust the relay drive output voltage.

[0013] In a possible implementation, the first power converter is a step-down conversion DCDC, a step-up conversion DCDC, or a step-up / step-down conversion DCDC.

[0014] In a possible implementation, the second power converter is used to supply power to the control unit and is a step-down converter DCDC or a low voltage drop linear regulator.

[0015] In a possible implementation, the control unit includes a logic device capable of outputting the first control signal and / or the second control signal.

[0016] The beneficial effects of the present invention are as follows: for the relay driving power supply, the present invention adopts switch control to adjust the output feedback resistance of the power converter, so as to adjust and change the output voltage of the power converter, so that when the relay is started, a higher voltage is output, so that the relay can quickly realize state conversion; and at other times including the relay holding stage, the power converter outputs a lower voltage, so as to reduce the power consumption of the relay and the control system, reduce the temperature rise, and extend the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A circuit structure diagram of a first embodiment of a relay energy-saving drive control circuit provided by the present invention; Figure 2 A circuit structure diagram of a second embodiment of a relay energy-saving drive control circuit provided by the present invention; Figure 3 A circuit structure diagram of a third embodiment of a relay energy-saving drive control circuit provided by the present invention; Figure 4 A circuit structure diagram of a fourth embodiment of a relay energy-saving drive control circuit provided by the present invention; Figure 5 A circuit structure diagram of a fifth embodiment of a relay energy-saving drive control circuit provided by the present invention; Figure 6 A signal waveform diagram of an implementation manner of a control signal output by a control unit provided by the present invention. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0020] The descriptions of "first", "second", etc. involved in the embodiments of the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the technical features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0021] The "embodiment" provided herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] See also Figure 1-Figure 6 In order to achieve the purpose of outputting a higher voltage when starting the relay so that the relay can quickly achieve state conversion, and making the power converter output a lower voltage at other times including the relay holding stage, the present invention provides a relay energy-saving drive control circuit, including: The first power converter (i.e., power converter 1), whose input terminal is connected to the positive terminal of the input power supply, is used to convert the input power supply voltage to obtain a conversion voltage; A feedback resistor, a first end of which is connected to the negative terminal of the input power supply, and a second end of which is connected to the output terminal of the first power converter, wherein the resistance of the feedback resistor is adjustable and is used to adjust the conversion voltage to obtain the relay drive output voltage.

[0023] It should be noted that a relay usually includes a drive coil and a load contact. The drive control of a relay refers to controlling the power on or off of its coil to achieve the purpose of controlling the closing or opening of its contacts. The relay drive control switch can be a mechanical switch or an electronic switch; it can control the positive pole of the relay drive power supply or the negative pole of the relay drive power supply. After the relay is selected, the resistance of its coil is usually a fixed value, and the drive power consumption mainly depends on the voltage of the relay drive power supply. For the drive control of the relay, usually, a higher drive power needs to be provided in the short time of starting the relay, while only a smaller drive power is required during the relay holding stage.

[0024] Furthermore, the relay driving power supply is the output of the power converter 1 , and the power converter 1 is usually a step-down conversion DCDC, a step-up conversion DCDC, or a step-up / step-down conversion DCDC.

[0025] Compared with the prior art, the present invention adopts switch control to adjust the output feedback resistance of the power converter for the relay driving power supply, so as to adjust and change the output voltage of the power converter, so as to output a higher voltage when starting the relay, so that the relay can quickly realize state transition; and at other times including the relay holding stage, the power converter outputs a lower voltage to reduce the power consumption of the relay and the control system, reduce the temperature rise, and extend the service life.

[0026] In a preferred embodiment, see Figure 2The feedback resistor includes a first resistor R1 and a second resistor R2, wherein the first end of the first resistor is connected to the output end of the first power converter, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the output end of the first power converter; wherein at least one of the first resistor and the second resistor has an adjustable resistance.

[0027] It should be noted that VFB is the error amplifier feedback control input for adjusting the output power supply voltage Vo (i.e., the relay drive output voltage) inside the first power converter, and its voltage VFB is the internal reference power supply voltage, which is a fixed value. R1 and R2 are feedback control resistors for adjusting the output power supply voltage Vo.

[0028] In a possible implementation, the calculation formula of the relay drive output voltage is: ; in, is the relay drive output voltage, VFB is the internal reference power supply voltage of the first power converter, R1 is the first resistor, R2 is the second resistor.

[0029] Generally, for the selected power converter 1, its VFB is a fixed value, and the resistance values ​​of R1 and R2 are adjusted to adjust the value in formula 1. The output power supply voltage Vo can be adjusted by adjusting the ratio of the resistor value. In practical applications, one resistor value can usually be fixed, and the other resistor value can be adjusted to achieve this. In addition, in order to adjust the resistance value, adjustable resistors, programmable control resistors, series-parallel resistors, etc. are usually used.

[0030] In a preferred embodiment, a parallel resistor R3 is added across R1 or R2, and a control switch is added to achieve the purpose of adjusting the output voltage Vo. Figure 3 , the feedback resistor further includes a third resistor R3, a first end of the third resistor is connected to the common end of the first resistor and the second resistor; the control circuit further includes a first control switch, two ends of the first control switch are respectively connected to one end of the second resistor and one end of the third resistor; The resistance value of the feedback resistor is changed by changing the opening and closing state of the first control switch.

[0031] Optionally, a parallel resistor and a control switch may be added at both ends of R1. For the control switch 1, a mechanical switch or an electronic switch may be used. Preferably, the electronic switch may be an NMOS tube, as follows Figure 4 and Figure 5Q1 in the circuit. The advantages of using NMOS tubes are: simple and reliable control, low cost, fast control response, small size, small feedback loop area, small power supply noise, and small on-resistance.

[0032] The control and adjustment method for the output power supply voltage Vo (i.e., the relay drive output voltage) is as follows: 1) When the control switch 1 is in the off state, the output power voltage Vo of the power converter 1 can be calculated according to formula 1.

[0033] 2) When the control switch 1 is in the closed state, R3 is connected in parallel across R2. The calculation formula for the resistance value R23 after parallel connection is as follows: ; At this time, the output power voltage Vo of the power converter 1 is calculated as follows: ; Since R23<R2, the ratio Therefore, the output power supply voltage Vo will increase.

[0034] Furthermore, the specific implementation of relay energy-saving drive control is as follows: 1) When the control relay does not need to be driven, or when the relay state transition is stable and only a small holding power is required, the control switch 1 can be turned off. At this time, the output power voltage Vo of the power converter 1 is low (VoL) to reduce the power consumption of the relay and the control system, thereby achieving energy saving.

[0035] 2) When the relay needs to be started, the control switch 1 can be closed. At this time, the output power voltage Vo of the power converter 1 is relatively high (VoH), which can enable the relay to quickly achieve state conversion.

[0036] In a preferred embodiment, Figure 4 and Figure 5 Two preferred control methods for controlling the switch Q1 are provided. Specifically, Figure 4 , the feedback resistor includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit further includes a second power converter (i.e., power converter 2), a control unit, a MOS tube, a fourth resistor and a fifth resistor; the input end of the second power converter is connected to the output end of the first power converter, and the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the fourth resistor; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube, and the second end of the fifth resistor is connected to the source of the MOS tube and the second end of the second resistor; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a first control signal, and the first control signal is used to control the on-off state of the MOS tube to adjust the relay drive output voltage.

[0037] Generally, the power converter 2 is the power supply for the logic device in the control unit, which is usually a step-down converter DCDC or a low-dropout linear regulator (LDO). In order to reduce the impact of power supply noise on the logic device, a low-dropout linear regulator (LDO) is usually used to power it. For a low-dropout linear regulator, as its input power supply voltage increases, its own power consumption will also increase under the premise of meeting the application. The input power supply of the power converter 2 can be the output of the power converter 1.

[0038] It should be noted that the control switch Q1 is controlled by a separate energy-saving control signal to control and adjust the output voltage Vo of the power converter 1. The control switch Q1 is preferably an NMOS tube, and R4 and R5 are control input protection resistors of Q1.

[0039] The energy-saving control signal of the control system can control the closing or opening of Q1 at any appropriate time to flexibly control and adjust the output voltage Vo of the power converter 1 .

[0040] The calculation method of the corresponding output voltage Vo is: 1) When Q1 is disconnected, its off-equivalent resistance is usually much larger than the resistance values ​​of R2 and R3, and the output voltage Vo of the power converter 1 can still be calculated according to Formula 1.

[0041] 2) When Q1 is closed, its on-resistance is usually much smaller than the resistance values ​​of R2 and R3, and the output voltage Vo of the power converter 1 can still be calculated according to Formula 3.

[0042] In addition, specific Figure 5 , the feedback resistor includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit also includes a second power converter, a control unit, a MOS tube, a first capacitor, a first diode, a fourth resistor, a fifth resistor and a sixth resistor; the input end of the second power converter is connected to the output end of the first power converter, and the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the sixth resistor and the first end of the first capacitor; the second end of the sixth resistor is connected to the positive end of the first diode; the second end of the first capacitor is connected to the first end of the fourth resistor and the negative end of the first diode; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube; the second end of the fifth resistor is connected to the source of the MOS tube, the second end of the second resistor and the positive end of the first diode; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a second control signal, and the second control signal is used to control the on / off state and delay state of the MOS tube to adjust the relay drive output voltage.

[0043] In an optional embodiment, the control unit includes a logic device capable of outputting the first control signal and / or the second control signal.

[0044] It should be noted that Figure 5 Another control method of the present invention uses the relay control signal to control Q1 at the same time. Specifically, only within the set time (t1) after the relay is started (the relay control signal is ON), the control switch Q1 is closed and the power converter 1 outputs a higher voltage (VoH), so that the relay can quickly achieve state conversion. At other times outside the set time (t1), the control switch Q1 is in the off state, and the output voltage of the power converter 1 is low (VoL) to reduce power consumption and extend the service life of the relay.

[0045] Among them, the setting time t1 is mainly determined by Figure 5 The capacitance of capacitor C1, the resistance of resistor R4, the resistance of resistor R5, and the switch characteristics of Q1 determine the time. Diode D1 and resistor R6 are mainly used to stabilize the control input of switch Q1. Usually, it takes hundreds of milliseconds from the start of the relay to the stable state transition, so the time t1 can be set to about 1 second.

[0046] This control method can save control ports and the control is simple and reliable.

[0047] Similarly, the corresponding output voltage Vo can also be calculated according to Formula 1 (VoL) or Formula 3 (VoH).

[0048] Please refer to further Figure 6 , Figure 6 for Figure 5 Example of waveform corresponding to the control method.

[0049] Figure 6 In the control system, before powering on and after powering off, it is in the shutdown state, and the output voltage of the power converter 1 (that is, the relay drive power supply voltage) is 0V. When the control system is turned on, its drive power supply voltage is high (VoH) only within the set time t1 of starting the relay. At other times, including when the relay does not need to be driven and during the relay holding stage, its drive power supply voltage is low (VoL) to reduce the power consumption of the relay and the control system and extend the service life.

[0050] In summary, the beneficial effects of the present invention are as follows: for the relay driving power supply, the present invention adopts switch control to adjust the output feedback resistance of the power converter, so as to adjust and change the output voltage of the power converter, so as to output a higher voltage when starting the relay, so that the relay can quickly realize state transition; and at other times including the relay holding stage, the power converter outputs a lower voltage to reduce the power consumption of the relay and the control system, reduce the temperature rise, and extend the service life.

[0051] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A relay energy-saving drive control circuit, characterized in that: include: A first power converter, whose input terminal is connected to the positive terminal of the input power supply, and is used to convert the input power supply voltage to obtain a conversion voltage; A feedback resistor, a first end of which is connected to the negative terminal of the input power supply, and a second end of which is connected to the output terminal of the first power converter, wherein the resistance of the feedback resistor is adjustable and is used to adjust the conversion voltage to obtain the relay drive output voltage.

2. The relay energy-saving drive control circuit according to claim 1, characterized in that: The feedback resistor includes a first resistor and a second resistor, wherein the first end of the first resistor is connected to the output end of the first power converter, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the output end of the first power converter; wherein at least one of the first resistor and the second resistor has an adjustable resistance.

3. The relay energy-saving drive control circuit according to claim 2, characterized in that: The calculation formula of the relay drive output voltage is: ； in, is the relay drive output voltage, VFB is the internal reference power supply voltage of the first power converter, R1 is the first resistor, R2 is the second resistor.

4. The relay energy-saving drive control circuit according to claim 2, characterized in that: The feedback resistor further includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; the control circuit further includes a first control switch, two ends of the first control switch are respectively connected to one end of the second resistor and one end of the third resistor; The resistance value of the feedback resistor is changed by changing the opening and closing state of the first control switch.

5. The relay energy-saving drive control circuit according to claim 4, characterized in that: The calculation formula of the relay drive output voltage is: ； in, , is the relay drive output voltage, VFB is the internal reference power supply voltage of the first power converter, R1 is the first resistor, R2 is the second resistor, R3 is the third resistor.

6. The relay energy-saving drive control circuit according to claim 2, characterized in that: The feedback resistor further includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit further includes a second power converter, a control unit, a MOS tube, a fourth resistor and a fifth resistor; the input end of the second power converter is connected to the output end of the first power converter, the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the fourth resistor; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube, the second end of the fifth resistor is connected to the source of the MOS tube and the second end of the second resistor; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a first control signal, and the first control signal is used to control the on-off state of the MOS tube to adjust the relay drive output voltage.

7. The relay energy-saving drive control circuit according to claim 2, characterized in that: The feedback resistor further includes a third resistor, a first end of the third resistor is connected to a common end of the first resistor and the second resistor; The control circuit also includes a second power converter, a control unit, a MOS tube, a first capacitor, a first diode, a fourth resistor, a fifth resistor and a sixth resistor; the input end of the second power converter is connected to the output end of the first power converter, and the output end of the second power converter is connected to the input end of the control unit; the output end of the control unit is connected to the first end of the sixth resistor and the first end of the first capacitor; the second end of the sixth resistor is connected to the positive end of the first diode; the second end of the first capacitor is connected to the first end of the fourth resistor and the negative end of the first diode; the second end of the fourth resistor is connected to the first end of the fifth resistor and the gate of the MOS tube; the second end of the fifth resistor is connected to the source of the MOS tube, the second end of the second resistor and the positive end of the first diode; the drain of the MOS tube is connected to the second end of the third resistor; The control unit is used to generate a second control signal, and the second control signal is used to control the on / off state and delay state of the MOS tube to adjust the relay drive output voltage.

8. The relay energy-saving drive control circuit according to any one of claims 1 to 7, characterized in that: The first power converter is a step-down converter DCDC, a step-up converter DCDC, or a step-up / step-down converter DCDC.

9. The relay energy-saving drive control circuit according to any one of claims 6 to 7, characterized in that: The second power converter is used to supply power to the control unit and is a step-down converter DCDC or a low voltage drop linear regulator.

10. The relay energy-saving drive control circuit according to any one of claims 6 to 7, characterized in that: The control unit includes a logic device capable of outputting the first control signal and / or the second control signal.

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