Contactor control circuit and method, substrate and contactor

Abstract

The invention provides a contactor control circuit and method, a substrate and a contactor. The circuit comprises a contactor coil, a voltage acquisition circuit, a current acquisition circuit, a switching tube, a PWM drive circuit and a main control circuit. The voltage acquisition circuit performs voltage sampling on the input voltage to obtain a voltage signal; when the voltage value of the voltage signal is greater than the minimum pull-in voltage, the master control circuit outputs a PWM control signal; the PWM driving circuit outputs a PWM driving signal to drive the switching tube according to the PWM control signal; when the switch tube is switched on, the current acquisition circuit samples the current of the contactor coil to obtain a coil current signal; and the master control circuit adjusts the frequency, the opening time, the opening duration, the closing time and the closing duration of the PWM control signal according to the voltage value of the voltage signal when the contactor performs the pull-in maintenance operation. The contactor is controlled to be in a wide voltage range, and the current in the contactor coil is constant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of contactor control, and in particular to a contactor control circuit, a contactor control method, a substrate and a contactor. BACKGROUND

[0002] As a widely used control electrical product, the working principle of a contactor is that a contactor coil sleeved on a static iron core generates an electromagnetic field after passing through an electric current, and a dynamic iron core is attracted to the static iron core under the action of the magnetic field, thereby driving the main circuit contact on the dynamic iron core to close, so as to achieve the purpose of small-current switch control of three-phase power large-current load on-off.

[0003] The contactor is an inductive device, and a large current is required when the contactor is controlled to perform an attraction operation. When the contactor completes the attraction operation and performs an attraction maintenance operation, a small current is required. In related technologies, a PWM driving circuit is often used to drive the contactor to perform the attraction operation, the attraction maintenance operation and the release operation.

[0004] Since the current required by the contactor to perform the attraction maintenance operation is small and the power consumption is low, the duty cycle of the PWM signal used to drive the contactor is also small. For the low-voltage electrical industry, the contactor often needs to work in a wide voltage environment. As the voltage increases, the duty cycle of the required PWM signal is lower. However, the traditional fixed frequency and continuous output PWM signal driving method of the contactor means that as the voltage rises, the duty cycle of the PWM signal needs to be reduced to control the constant current in the contactor coil. However, the controllable voltage range of this method is limited. After the duty cycle of the PWM signal is reduced to a certain extent, the current in the contactor coil cannot be adjusted and will rise with the increase of the voltage. When the contactor works in a high voltage range, the current in the contactor coil will also be large, which will further cause the temperature of the contactor coil to rise. SUMMARY

[0005] The present application provides a contactor control circuit, a contactor control method, a substrate and a contactor to control the constant current in the contactor coil when the contactor works in a wide voltage range, and reduce the temperature rise of the contactor coil.

[0006] In a first aspect, the present application provides a contactor control circuit, which comprises a contactor coil, a voltage acquisition circuit, a current acquisition circuit, a switch tube, a PWM driving circuit and a master control circuit.

[0007] The first end of the contactor coil is connected to an input voltage, the second end of the contactor coil is electrically connected to the second end of the switch tube, the first end of the switch tube is electrically connected to the input end of the current acquisition circuit, and the control end of the switch tube is electrically connected to the output end of the PWM driving circuit; the input end of the voltage acquisition circuit is connected to the input voltage, and the output end of the voltage acquisition circuit is electrically connected to the first end of the main control circuit; the input end of the PWM driving circuit is electrically connected to the second end of the main control circuit, and the output end of the current acquisition circuit is electrically connected to the third end of the main control circuit;

[0008] The voltage acquisition circuit is configured to sample the input voltage to obtain a voltage signal.

[0009] The main control circuit is configured to output a PWM control signal when the voltage value of the voltage signal is greater than a minimum pull-in voltage.

[0010] The PWM driving circuit is configured to output a PWM driving signal according to the PWM control signal to drive the switch tube, so that the contactor performs a pull-in operation.

[0011] The current acquisition circuit is configured to sample a current flowing through the contactor coil to obtain a coil current signal when the PWM driving signal drives the switch tube to be turned on.

[0012] The main control circuit is further configured to adjust the frequency of the PWM control signal, and adjust the opening time, the opening duration, the closing time and the closing duration of the PWM control signal according to the voltage value of the voltage signal when the contactor performs a pull-in maintenance operation, so that the current value of the coil current signal remains a constant current value, wherein the opening duration is the duration of turning on the PWM control signal, and the closing duration is the duration of turning off the PWM control signal.

[0013] In a possible design, the current acquisition circuit includes a first diode, a first resistor, a second resistor and a first capacitor.

[0014] The anode of the first diode is electrically connected to the first end of the first resistor, the first end of the second resistor and the first end of the switch tube, respectively.

[0015] The second end of the second resistor is electrically connected to the first end of the first capacitor and the third end of the main control circuit, respectively.

[0016] The cathode of the first diode, the second end of the first resistor and the second end of the first capacitor are all grounded.

[0017] In a possible design, the voltage acquisition circuit includes a third resistor, a fourth resistor, and a fifth resistor.

[0018] A first end of the third resistor is connected to the input voltage, a second end of the third resistor is electrically connected to a first end of the fourth resistor, and a second end of the fourth resistor is electrically connected to a first end of the fifth resistor and a first end of the main control circuit.

[0019] A second end of the fifth resistor is grounded.

[0020] In a possible design, the contactor control circuit further includes a control power supply circuit, an EMC circuit, a rectifier circuit, a freewheeling circuit, and a fast release circuit.

[0021] An input end of the control power supply circuit is connected to the input voltage, a first output end of the control power supply circuit is electrically connected to a fourth end of the main control circuit, and a second output end of the control power supply circuit is electrically connected to a power supply end of the PWM drive circuit.

[0022] An input end of the EMC circuit is used to connect to a power supply voltage, an output end of the EMC circuit is electrically connected to an input end of the rectifier circuit, and an output end of the rectifier circuit is electrically connected to a first end of the freewheeling circuit and a first end of the contactor coil.

[0023] A second end of the freewheeling circuit is electrically connected to a first end of the fast release circuit, a second end of the fast release circuit is electrically connected to a second end of the switch tube, and a third end of the fast release circuit is electrically connected to a fifth end of the main control circuit.

[0024] The control power supply circuit is configured to supply power to the main control circuit and the PWM drive circuit.

[0025] The EMC circuit is configured to perform anti-interference processing on the connected power supply voltage.

[0026] The rectifier circuit is configured to rectify the power supply voltage.

[0027] The freewheeling circuit is configured to provide a current path of the contactor coil when the switch tube is turned off, so that the contactor coil performs freewheeling.

[0028] The fast release circuit is configured to provide a current path of the contactor coil according to a control signal provided by the fifth end of the main control circuit when the switch tube is turned off, so that the contactor coil performs freewheeling, and is further configured to provide a current consumption path of the contactor coil according to the control signal provided by the fifth end of the main control circuit when a voltage value of the voltage signal is less than a minimum release voltage, so that the contactor coil performs current release.

[0029] In a second aspect, the application provides a contactor control method, which is applied to the contactor control circuit according to the first aspect;

[0030] sampling the input voltage to obtain a voltage signal;

[0031] outputting a PWM control signal when the voltage value of the voltage signal is greater than the minimum pull-in voltage;

[0032] outputting a PWM drive signal according to the PWM control signal to drive the switch tube, so that the contactor performs a pull-in operation;

[0033] sampling a current flowing through the contactor coil to obtain a coil current signal when the PWM drive signal drives the switch tube to be turned on;

[0034] adjusting the frequency of the PWM control signal, and adjusting the turn-on time, the turn-on duration, the turn-off time and the turn-off duration of the PWM control signal according to the voltage value of the voltage signal, so that the current value of the coil current signal remains a constant current value, when the contactor performs a pull-in maintenance operation, wherein the turn-on duration is the duration of turning on the PWM control signal, and the turn-off duration is the duration of turning off the PWM control signal.

[0035] In a possible design, the adjusting the frequency of the PWM control signal according to the voltage value of the voltage signal when the contactor performs a pull-in maintenance operation includes:

[0036] dividing the voltage value of the voltage signal into a preset number of voltage value intervals when the contactor performs a pull-in maintenance operation;

[0037] setting a corresponding frequency of the PWM control signal for any voltage value interval.

[0038] In a possible design, the adjusting the turn-on time, the turn-on duration, the turn-off time and the turn-off duration of the PWM control signal to keep the current value of the coil current signal as a constant current value includes:

[0039] when the power supply voltage is an alternating signal:

[0040] the turn-on time of the PWM control signal is a zero-crossing point of the alternating signal, and the turn-off time of the PWM control signal is a peak point of the alternating signal;

[0041] adjusting the turn-on duration and the turn-off duration of the PWM control signal according to the voltage value of the voltage signal;

[0042] When the power supply voltage is a DC signal:

[0043] The PWM control signal is turned on at a first fixed time, and the PWM control signal is turned off at a second fixed time.

[0044] The on and off durations of the PWM control signal are adjusted based on the voltage value of the voltage signal.

[0045] In one possible design, the method further includes:

[0046] When the power supply voltage is an AC signal:

[0047] If the effective value of the AC signal during a 1 / 4 cycle is greater than the minimum pull-in voltage by a preset multiple, a PWM control signal is output; or, the cumulative power of the contactor coil is calculated according to a preset interval time, and when the cumulative power is less than a preset power threshold, the maximum duty cycle of the PWM control signal is set to 100%; when the cumulative power is greater than or equal to the preset power threshold, the duty cycle of the PWM control signal is adjusted according to the current value of the coil current signal, so that the contactor performs a pull-in operation.

[0048] Thirdly, this application provides a substrate including: a contactor control circuit as described in the first aspect.

[0049] Fourthly, this application provides a contactor comprising: a substrate as described in the third aspect.

[0050] The beneficial effects of the embodiments of this application are as follows:

[0051] In the embodiment of the present application, the input voltage is sampled by the voltage sampling circuit to obtain a voltage signal, the main control circuit outputs a PWM control signal when the voltage value of the voltage signal is greater than the minimum attraction voltage, the PWM driving circuit outputs a PWM driving signal according to the PWM control signal to drive the switching tube, so that the contactor performs the attraction operation, the current sampling circuit samples the current flowing through the contactor coil when the switching tube is turned on by the PWM driving signal to obtain a coil current signal, and the main control circuit adjusts the frequency of the PWM control signal, and adjusts the opening time, the opening time length, the closing time and the closing time length of the PWM control signal according to the size of the voltage value of the voltage signal when the contactor performs the attraction and maintenance operation, so that the current value of the coil current signal remains a constant current value. According to the size of the voltage value of the voltage signal, the frequency of the PWM control signal is adjusted, the switching loss and temperature rise of the switching tube are reduced, the voltage range in which the current value of the contactor coil remains a constant current value is expanded, and at the same time, the current size of the contactor coil is controlled by intermittently opening and closing the PWM control signal, so that the current value in the contactor coil remains a constant current value when the contactor works in a wide voltage range. The problem that the current in the contactor coil increases with the increase of the voltage, and then the temperature of the contactor coil increases, is solved. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art according to these drawings.

[0053] Figure 1 The circuit structure schematic diagram of a contactor control circuit provided in the embodiment of the present application is shown in the figure.

[0054] Figure 2 The circuit structure schematic diagram of another contactor control circuit provided in the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0055] In the present application, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one of the following" or similar expressions means any combination of these items, including single or multiple items in any combination. For example, at least one of a, b, or c alone can represent: a alone, b alone, c alone, combination of a and b, combination of a and c, combination of b and c, or combination of a, b and c, where a, b, c can be single or multiple. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0056] The terms "center", "longitudinal", "transverse", "upper", "lower", "left", "right", "front", "back", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0057] The terms "connected" and "connected" should be broadly understood, for example, the "connected" or "connected" of the circuit structure can mean physical connection, but also means electrical connection or signal connection, for example, it can be directly connected, that is, physically connected, or indirectly connected through at least one element in the middle, as long as the circuit is connected, it can also be the internal connection of two elements; Signal connection can be signal connection through circuit, but also means signal connection through media medium, such as radio waves. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In order to solve the problem that in the related art, when the contactor works in a wide voltage range, the current in the contactor coil will increase with the increase of the voltage, thereby causing the temperature of the contactor coil to rise, the present application provides a contactor control circuit, which is described with reference to Figure 1 , Figure 1 The circuit structure schematic diagram of a contactor control circuit provided by the embodiment of the present application is shown in Figure 1 The contactor control circuit 1000 can include a contactor coil L, a voltage acquisition circuit 200, a current acquisition circuit 100, a switch tube Q1, a PWM drive circuit, and a main control circuit MCU.

[0059] The first end of the contactor coil L is connected to the input voltage HV, the second end of the contactor coil L is electrically connected to the second end of the switch tube Q1, the first end of the switch tube Q1 is electrically connected to the input end of the current acquisition circuit 100, and the control end of the switch tube Q1 is electrically connected to the output end of the PWM drive circuit; the input end of the voltage acquisition circuit 200 is connected to the input voltage HV, and the output end of the voltage acquisition circuit 200 is electrically connected to the first end ADC2 of the main control circuit MCU; the input end of the PWM drive circuit is electrically connected to the second end PWM0 of the main control circuit MCU, and the output end of the current acquisition circuit 100 is electrically connected to the third end ADC1 of the main control circuit MCU.

[0060] The voltage acquisition circuit 200 is configured to sample the input voltage HV to obtain a voltage signal.

[0061] The main control circuit MCU is configured to output a PWM control signal PWM-C when the voltage value of the voltage signal is greater than the minimum magnetizing voltage.

[0062] The PWM drive circuit is configured to output a PWM drive signal PWM-D according to the PWM control signal PWM-C to drive the switch tube Q1, so that the contactor performs the magnetizing operation.

[0063] The current acquisition circuit 100 is configured to sample the current flowing through the contactor coil L when the PWM drive signal PWM-D drives the switch tube Q1 to be turned on, to obtain a coil current signal.

[0064] The main control circuit MCU is further configured to adjust the frequency of the PWM control signal PWM-C, and adjust the opening time, the opening time length, the closing time and the closing time length of the PWM control signal PWM-C according to the voltage value of the voltage signal, so that the current value of the coil current signal remains a constant current value, when the contactor performs the magnetizing maintenance operation, wherein the opening time length is the duration of the opening of the PWM control signal PWM-C, and the closing time length is the duration of the closing of the PWM control signal PWM-C.

[0065] In the embodiment of the application, referring to Figure 1 , the PWM control signal PWM-C output by the main control circuit MCU controls the state of the switch tube Q1, realizes the power-on and power-off of the contactor coil L, and further realizes the driving of the contactor to perform the magnetizing operation, the magnetizing maintenance operation and the release operation.

[0066] The switch tube Q1 in the application can be a bipolar switch tube or a field effect switch tube, etc. For example, when the switch tube Q1 is a bipolar switch tube, the control end is the base of the bipolar switch tube, the first end can be the collector or the emitter of the bipolar switch tube, and the corresponding second end can be the emitter or the collector of the bipolar switch tube; when the switch tube Q1 is a field effect switch tube, the control end is the gate of the field effect switch tube, the first end can be the drain or the source of the field effect switch tube, and the corresponding second end can be the source or the drain of the field effect switch tube.

[0067] When the switch tube Q1 is an N-type MOS tube, the control end of the switch tube Q1 is the gate of the N-type MOS tube, the first end of the switch tube Q1 is the source of the N-type MOS tube, and the corresponding second end of the switch tube Q1 is the drain of the N-type MOS tube.

[0068] The contactor control circuit 1000 in the application can include a voltage acquisition circuit 200 and a current acquisition circuit 100, wherein the voltage acquisition circuit 200 performs voltage sampling on the input voltage HV to obtain a voltage signal, the master control circuit MCU performs root mean square value calculation on the voltage signal to obtain a voltage value of the voltage signal, when the voltage value of the voltage signal is greater than the minimum attraction voltage, it is determined that the contactor needs to be driven to perform attraction operation, at this time, the master control circuit MCU outputs a PWM control signal PWM-C; the PWM driving circuit outputs a PWM driving signal PWM-D after performing signal processing such as amplification on the PWM control signal PWM-C, to drive the switch tube Q1, so that the contactor performs attraction operation.

[0069] When the PWM driving signal PWM-D drives the switch tube Q1 to be turned on, the contactor coil L is energized, and since the current of the contactor coil L will not be suddenly changed, when the master control circuit MCU outputs the PWM control signal PWM-C, the current acquisition circuit 100 is triggered at the same time to sample the current flowing through the contactor coil L, so that the current flowing through the contactor coil L, i.e. the coil current signal, can be obtained.

[0070] The PWM driving circuit is used for power amplification and isolation of the PWM control signal PWM-C output by the master control circuit MCU, and outputs a PWM driving signal PWM-D to realize control of the switch tube Q1. The PWM driving circuit is prior art, which can be realized by using existing PWM driving chips, and the application does not make specific limitation on this.

[0071] In order to make the contactor work in a wide voltage range, the current in the contactor coil does not increase with the increase of the voltage, so that the current value of the coil current signal remains a constant current value, and the temperature rise of the contactor coil is reduced. The main control circuit in the application adjusts the frequency of the PWM control signal PWM-C according to the voltage value of the voltage signal, and adjusts the opening time, opening duration, closing time and closing duration of the PWM control signal PWM-C, so that the current value of the coil current signal remains a constant current value. Specifically, by reducing the frequency of the PWM control signal PWM-C, the number of times of sudden current generated by the contactor coil L when the switch tube Q1 is turned on and turned off is reduced, the switching loss and temperature rise of the switch tube Q1 are reduced, and the voltage range in which the current value of the coil current signal of the contactor coil L remains a constant current value is increased.

[0072] In addition, according to the size of the voltage value of the voltage signal, the opening time, opening duration, closing time and closing duration of the PWM control signal PWM-C are adjusted at the same time, that is, the PWM control signal PWM-C is intermittently turned on and turned off, the release of the current in the contactor coil L is realized, and the current size of the contactor coil L is controlled, so that the current value in the contactor coil remains a constant current value when the contactor works in a wide voltage range.

[0073] In the embodiment of the application, the voltage sampling circuit samples the input voltage to obtain a voltage signal, the main control circuit outputs a PWM control signal when the voltage value of the voltage signal is greater than the minimum attraction voltage, the PWM drive circuit outputs a PWM drive signal according to the PWM control signal to drive the switch tube, so that the contactor performs attraction operation, the current sampling circuit samples the current flowing through the contactor coil when the switch tube is turned on by the PWM drive signal to obtain a coil current signal, and the main control circuit adjusts the frequency of the PWM control signal and adjusts the opening time, opening duration, closing time and closing duration of the PWM control signal according to the size of the voltage value of the voltage signal when the contactor performs attraction and maintenance operation, so that the current value of the coil current signal remains a constant current value. According to the size of the voltage value of the voltage signal, the frequency of the PWM control signal is adjusted, the switching loss and temperature rise of the switch tube are reduced, the voltage range in which the current value of the contactor coil remains a constant current value is expanded, and the current size of the contactor coil is controlled by intermittently turning on and turning off the PWM control signal, so that the current value in the contactor coil remains a constant current value when the contactor works in a wide voltage range. The problem that the current in the contactor coil increases with the increase of the voltage and the temperature of the contactor coil is increased is solved.

[0074] In a possible embodiment, referring to Figure 2 , Figure 2Another circuit structure schematic diagram of the contactor control circuit provided by the embodiment of the present application is shown in FIG. 2. As shown in FIG. 2, the current collection circuit 100 can include a first diode D1, a first resistor R1, a second resistor R2, and a first capacitor C1. Figure 2

[0075] The anode of the first diode D1 is electrically connected with the first end of the first resistor R1, the first end of the second resistor R2, and the first end of the switch tube Q1 respectively.

[0076] The second end of the second resistor R2 is electrically connected with the first end of the first capacitor C1 and the third end ADC1 of the main control circuit MCU respectively.

[0077] The cathode of the first diode D1, the second end of the first resistor R1, and the second end of the first capacitor C1 are grounded.

[0078] In the embodiment, the current flowing through the contactor coil L is sampled by the ADC (Analog to Digital Converter) of the main control circuit MCU. The main control circuit MCU triggers the ADC to sample the current flowing through the contactor coil L by the output PWM control signal PWM-C. The main control circuit MCU can effectively filter out the peak voltage of the current sampling resistor (i.e., the first resistor R1) by adjusting the ADC sampling clock period, so as to avoid collecting the ripple voltage (or glitch signal) and reduce the cost of the filtering circuit while improving the precision of the collected coil current signal.

[0079] When the switch tube Q1 is turned on by the PWM driving signal PWM-D, the current of the contactor coil L will not be suddenly changed, and flows through the first diode D1 and the first resistor R1. The voltage of the first resistor R1 can be collected to calculate the current of the contactor coil L. The first diode D1 has the function of clamping voltage, and can prevent the problem that the switch tube Q1 is turned on and then instantaneously turned off due to the reduction of the voltage difference between the gate and the source of the switch tube Q1 when the current of the contactor coil L is too large.

[0080] The current of the contactor coil L is equal to VADC1 / r, wherein VADC1 is the voltage value collected by the third end ADC1 of the main control circuit MCU, and r is the resistance value after the parallel connection of the resistance value of the first resistor R1 and the equivalent resistance value of the first diode D1. By setting the resistance value of the first resistor R1, it can be ensured that the contactor coil L is saturated due to the clamping effect of the first diode D1 when the contactor performs the attraction operation, so that the current collection circuit can accurately collect the current of the contactor coil L.

[0081] ​The current flowing through the contactor coil L is directly sampled by the ADC of the main control circuit MCU in the application, compared with the traditional sampling method through the circuit composed of resistors and operational amplifiers, the use of signal amplification and filtering process such as operational amplifier is saved, and the cost is saved.

[0082] In a possible embodiment, referring to Figure 2 , the voltage acquisition circuit 200 comprises a third resistor R3, a fourth resistor R4 and a fifth resistor R5.

[0083] The first end of the third resistor R3 is connected to the input voltage HV, the second end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is electrically connected to the first end of the fifth resistor R5 and the first end ADC2 of the main control circuit MCU.

[0084] The second end of the fifth resistor R5 is grounded.

[0085] The third resistor R3, the fourth resistor R4 and the fifth resistor R5 constitute a voltage dividing circuit, and the voltage of the fifth resistor R5 is acquired by the first end ADC2 of the main control circuit MCU, and then the voltage value of the input voltage can be calculated.

[0086] In a possible embodiment, referring to Figure 2 , the contactor control circuit 1000 further comprises a control power supply circuit, an EMC circuit, a rectifier circuit, a freewheeling circuit and a fast release circuit.

[0087] The input end of the control power supply circuit is connected to the input voltage HV, and the first output end of the control power supply circuit is electrically connected to the fourth end VCC of the main control circuit MCU; the second output end of the control power supply circuit is electrically connected to the power supply end VDD of the PWM drive circuit.

[0088] The input end of the EMC circuit is used to connect to the power supply voltage, the output end of the EMC circuit is electrically connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is electrically connected to the first end of the freewheeling circuit and the first end of the contactor coil L.

[0089] The second end of the freewheeling circuit is electrically connected to the first end of the fast release circuit, the second end of the fast release circuit is electrically connected to the second end of the switch tube Q1, and the third end of the fast release circuit is electrically connected to the fifth end IO of the main control circuit MCU.

[0090] The control power supply circuit is used to supply power for the main control circuit and the PWM drive circuit.

[0091] The EMC circuit is used to anti-interference process the connected power supply voltage.

[0092] The rectifier circuit is used to rectify the power supply voltage.

[0093] A freewheeling circuit is configured to provide a current path for the contactor coil to freewheel when the switch tube is turned off.

[0094] A fast release circuit is configured to provide a current path for the contactor coil to freewheel according to a control signal provided by the fifth terminal IO of the master control circuit when the switch tube is turned off, and to provide a current consumption path for the contactor coil to release current according to the control signal provided by the fifth terminal IO of the master control circuit when the voltage value of the voltage signal is less than the minimum release voltage.

[0095] The control power supply circuit is configured to perform level conversion on the input voltage HV to supply power to the master control circuit and the PWM drive circuit. The control power supply circuit can include an existing DCDC (Direct Current-Direct Current) conversion circuit and an LDO (Low-dropout regulator), which converts the input voltage HV into a voltage value required by the master control circuit and the PWM drive circuit. For example, the control power supply circuit converts the input voltage HV of 380V into a DC voltage of 24V to supply power to the PWM drive circuit, and converts the input voltage HV of 380V into a DC voltage of 3.3V to supply power to the master control circuit. The circuit structure of the control power supply circuit is not limited in the present application.

[0096] Since the PWM drive circuit is powered by the control power supply circuit, reducing the frequency of the PWM control signal and intermittently turning on and off the PWM control signal can effectively reduce the power of the PWM drive circuit. In addition, for the control power supply circuit using LDO voltage reduction, the temperature rise of the control power supply circuit can be effectively reduced under the condition of high input voltage.

[0097] The power supply voltage is an input signal of the contactor. The power supply voltage can be a direct current signal or an alternating current signal. For example, the power supply voltage can be a direct current signal of 110V, and the power supply voltage can also be an alternating current signal of 220V.

[0098] The EMC circuit is an existing electromagnetic interference protection circuit configured to perform anti-interference processing on the input voltage HV. The circuit structure of the EMC circuit is not limited in the present application. The rectifier circuit is an existing rectifier circuit configured to perform rectification processing on the power supply voltage to obtain the input voltage HV. When the power supply voltage is a direct current signal, the input voltage HV is a smooth direct current signal. When the power supply voltage is an alternating current signal, the input voltage HV is a pulsating direct current signal. The circuit structure of the rectifier circuit is not limited in the present application.

[0099] The functions of the freewheeling circuit and the fast release circuit will be introduced in combination with the control principle of the contactor control circuit: when the switch tube Q1 is turned on, the current of the contactor coil L will increase, and when the switch tube Q1 is turned off, the current of the contactor coil L will not change abruptly. The freewheeling circuit provides a current path for the contactor coil, and the fast release circuit provides a current path for the contactor coil L according to the control signal provided by the fifth end IO of the main control circuit MCU, so that the current of the contactor coil L returns to the other end of the contactor coil L through the freewheeling circuit and the fast release circuit, and the freewheeling of the contactor coil is realized.

[0100] When the voltage value of the voltage signal is less than the minimum release voltage, the contactor needs to be released, and the fast release circuit provides a current consumption path for the contactor coil L according to the control signal provided by the fifth end IO of the main control circuit MCU, and the impedance between the two ends of the fast release circuit will increase, so that the current of the contactor coil L is quickly released through the fast release circuit, so that the contactor coil is quickly released, and the purpose of controlling the release operation of the contactor is achieved.

[0101] The embodiment of the application also provides a contactor control method, which comprises:

[0102] S1, voltage sampling is performed on an input voltage to obtain a voltage signal.

[0103] S2, when the voltage value of the voltage signal is greater than the minimum attraction voltage, a PWM control signal is output.

[0104] S3, according to the PWM control signal, a PWM drive signal is output to drive the switch tube, so that the contactor performs the attraction operation.

[0105] S4, when the switch tube is turned on by the PWM drive signal, the current flowing through the contactor coil is sampled to obtain a coil current signal.

[0106] S5, when the contactor performs the attraction maintenance operation, the frequency of the PWM control signal is adjusted according to the size of the voltage value of the voltage signal, and the opening time, the opening time length, the closing time and the closing time length of the PWM control signal are adjusted, so that the current value of the coil current signal remains a constant current value, wherein the opening time length is the duration of the opening PWM control signal, and the closing time length is the duration of the closing PWM control signal.

[0107] The working principles of steps S1 to S5 have been introduced in the above embodiment, and will not be repeated here.

[0108] In the embodiment of the present application, the input voltage is sampled to obtain a voltage signal, and when the voltage value of the voltage signal is greater than the minimum attraction voltage, a PWM control signal is output; according to the PWM control signal, a PWM driving signal is output to drive the switching tube, so that the contactor performs the attraction operation; when the switching tube is turned on by the PWM driving signal, the current flowing through the contactor coil is sampled to obtain a coil current signal; when the contactor performs the attraction maintenance operation, according to the size of the voltage value of the voltage signal, the frequency of the PWM control signal is adjusted, and the opening time, the opening duration, the closing time and the closing duration of the PWM control signal are adjusted, so that the current value of the coil current signal remains a constant current value. According to the size of the voltage value of the voltage signal, the frequency of the PWM control signal is adjusted, the switching loss and temperature rise of the switching tube are reduced, and the voltage range in which the current value of the contactor coil remains a constant current value is expanded. At the same time, by intermittently opening and closing the PWM control signal, the current size of the contactor coil is controlled, so that the current value in the contactor coil remains a constant current value when the contactor works in a wide voltage range. The problem that the current in the contactor coil increases with the increase of the voltage, and then the temperature of the contactor coil increases, is solved.

[0109] In a possible embodiment, the above step S5 comprises:

[0110] S51, when the contactor performs the attraction maintenance operation, the voltage value of the voltage signal is divided into a preset number of voltage value intervals.

[0111] The preset number can be set by the user as needed.

[0112] The voltage value of the voltage signal is divided into a preset number of voltage value intervals. In an example, if the voltage value of the voltage signal ranges from 100V to 250V, the voltage value of the voltage signal can be divided into three voltage value intervals, the first voltage value interval is 100V-150V, the second voltage value interval is 150V-200V, and the third voltage value interval is 200V-250V.

[0113] S52, for any voltage value interval, set the corresponding frequency of the PWM control signal.

[0114] For each voltage value interval, the frequency of the corresponding PWM control signal is set. In this application, the frequency of the PWM control signal ranges from 12 kHz to 20 kHz. As the voltage increases, the frequency of the corresponding PWM control signal gradually decreases. In one example, for the first voltage value interval 100V-150V, the frequency of the corresponding PWM control signal is set to 18 kHz; for the second voltage value interval 150V-200V, the frequency of the corresponding PWM control signal is set to 15 kHz; for the third voltage value interval 200V-250V, the frequency of the corresponding PWM control signal is set to 12 kHz.

[0115] As the voltage increases, reducing the frequency of the PWM control signal not only reduces the switching loss of the switching tube Q1, but also reduces the temperature rise of the switching tube Q1, and at the same time, the voltage range in which the current value of the contactor coil L is kept constant can be expanded. In addition, reducing the frequency of the PWM control signal will reduce the number of times the contactor coil L produces a sudden current when the switching tube Q1 is turned on or off, which can effectively reduce the radiation of the contactor and improve the EMI (Electro Magnetic Interference) performance of the contactor.

[0116] In one possible embodiment, the above step S5 further comprises:

[0117] S53, when the power voltage is an alternating signal: the opening time of the PWM control signal is the zero-crossing point of the alternating signal, and the closing time of the PWM control signal is the peak point of the alternating signal.

[0118] By reducing the frequency of the PWM control signal, the voltage range in which the current value of the contactor coil L is kept constant can be improved, but the adjustment range is limited. If only the frequency of the PWM control signal is reduced to improve the voltage range in which the current value of the contactor coil L is kept constant, the frequency of the PWM control signal will decrease, which will cause the contactor coil L to produce noise and affect the user experience. Therefore, in addition to reducing the frequency of the PWM control signal, this application also adopts intermittent opening or closing of the PWM control signal to improve the voltage range in which the current value of the contactor coil L is kept constant.

[0119] Specifically, when the power voltage is an alternating signal, the opening time of the PWM control signal is the zero-crossing point of the alternating signal, and the closing time of the PWM control signal is the peak point of the alternating signal, i.e. the PWM control signal is opened at the zero-crossing point of the alternating signal and closed at the peak point of the alternating signal.

[0120] S54, according to the voltage value of the voltage signal, adjusting the opening duration and closing duration of the PWM control signal.

[0121] According to the voltage value of the voltage signal, the duration of turning on the PWM control signal (i.e. the on duration) and the duration of turning off the PWM control signal (i.e. the off duration) are adjusted. Specifically, when the voltage value of the voltage signal is in a low voltage range, the on duration of the PWM control signal is longer and the off duration of the PWM control signal is shorter; as the voltage value of the voltage signal increases, the off duration of the PWM control signal is gradually increased; when the voltage value of the voltage signal is in a high voltage range, the off duration of the PWM control signal is no longer increased.

[0122] In one example, if the voltage value of the voltage signal ranges from 100V to 250V, for a first voltage value interval 100V-150V, the on duration of the PWM control signal is set to 15ms and the off duration of the PWM control signal is set to 5ms; for a second voltage value interval 150V-200V, the on duration of the PWM control signal is set to 10ms and the off duration of the PWM control signal is set to 10ms; for a third voltage value interval 200V-250V, the on duration of the PWM control signal is set to 8ms and the off duration of the PWM control signal is set to 12ms.

[0123] S55, when the power voltage is a direct current signal: the on time of the PWM control signal is a first fixed time, and the off time of the PWM control signal is a second fixed time.

[0124] The first fixed time and the second fixed time can be set according to the needs of the user.

[0125] When the power voltage is a direct current signal, the PWM control signal is intermittently turned on and off according to a fixed period (i.e. the on time and the off time are fixed times).

[0126] S56, according to the voltage value of the voltage signal, adjusting the on duration and the off duration of the PWM control signal.

[0127] In one example, if the voltage value of the voltage signal ranges from 100V to 250V, for a first voltage value interval 100V-150V, the on duration of the PWM control signal is set to 15ms and the off duration of the PWM control signal is set to 5ms; for a second voltage value interval 150V-200V, the on duration of the PWM control signal is set to 10ms and the off duration of the PWM control signal is set to 10ms; for a third voltage value interval 200V-250V, the on duration of the PWM control signal is set to 8ms and the off duration of the PWM control signal is set to 12ms.

[0128] In the embodiment of the present application, the frequency of the PWM control signal is adjusted according to the voltage value of the voltage signal, and the start time, start duration, stop time and stop duration of the PWM control signal are adjusted at the same time. This control method can keep the current value of the contactor coil L constant when the input voltage is in a wide voltage range.

[0129] The present application can also adjust the frequency of the PWM control signal according to the voltage value of the voltage signal, and adjust the start time, start duration, stop time and stop duration of the PWM control signal, and adjust the duty cycle of the PWM control signal. Through the comprehensive adjustment of the frequency, start time, start duration, stop time, stop duration and duty cycle of the PWM control signal, the current value of the contactor coil L can be kept constant in the full voltage range.

[0130] When the input voltage is an AC signal, the peak current of the contactor coil L is the largest at the peak point of the AC signal. This sudden change of the burr is the main source of radiation. The present application turns off the PWM control signal at the peak point of the AC signal, which can reduce the radiation and improve the EMI performance of the contactor. In addition, due to the Miller capacitance of the switch tube Q1, the larger the input voltage, the larger the current burr of the switch tube Q1 when it is turned on and turned off. Turning off the PWM control signal at the peak point of the AC signal can further reduce the radiation and improve the EMI performance of the contactor.

[0131] In one possible embodiment, the contactor control method further comprises:

[0132] S6, when the input voltage is an AC signal: if the effective value of the 1 / 4 period of the AC signal is greater than the preset multiple of the minimum magnetizing voltage, output the PWM control signal; or, calculate the cumulative power of the contactor coil according to the preset interval time, and when the cumulative power is less than the preset power threshold, adjust the duty cycle of the PWM control signal to 100%; when the cumulative power is greater than the preset power threshold, adjust the frequency of the PWM control signal according to the voltage value of the voltage signal, and adjust the start time, start duration, stop time and stop duration of the PWM control signal.

[0133] The main control circuit calculates the root mean square value of the collected voltage signal and the coil current signal to obtain the effective value. When the power voltage is a direct current signal, the voltage signal collected for 1 ms or 5 ms is calculated for the root mean square value, and the effective value obtained will not have a significant difference. When the power voltage is an alternating current signal, the input voltage is a periodic signal. Taking 50 Hz commercial power as an example, since the period of 50 Hz commercial power is 20 ms, 5 ms is 1 / 4 of the period, which is less than the period. If the voltage signal collected for 5 ms is calculated for the root mean square value, the effective value obtained may be too large or too small. If the voltage signal collected for 10 ms is calculated for the root mean square value, the total time spent on calculation and attraction judgment will often exceed the design requirement time of the product, which cannot meet the design requirements.

[0134] In order to shorten the response time of the attraction operation in the contactor, when the power voltage is an alternating current signal, the voltage signal collected for 5 ms (i.e. 1 / 4 of the period) is calculated for the root mean square value. If the effective value of the 1 / 4 period alternating current signal is greater than the minimum attraction voltage by a preset multiple, the PWM control signal is output to make the contactor perform the attraction operation. The preset multiple can be 1.414. The voltage signal collected for 5 ms (i.e. 1 / 4 of the period) is calculated for the root mean square value, which can obtain the peak voltage of the alternating current signal. Comparing it with the minimum attraction voltage by 1.414 times, i.e. comparing the peak voltage of the alternating current signal with the peak voltage of the minimum attraction voltage. If the effective value of the 1 / 4 period alternating current signal is greater than the minimum attraction voltage by 1.414 times, it is determined that the input voltage is greater than the minimum attraction voltage, and the contactor can be controlled to perform the attraction operation, which can effectively shorten the attraction judgment time.

[0135] Since the above method directly compares the input voltage with the minimum attraction voltage, for the input voltage in the high voltage range, the input voltage greater than the minimum attraction voltage can be directly judged, which can effectively shorten the attraction judgment time. However, for the input voltage in the low voltage range, the voltage signal collected for 10 ms is calculated for the root mean square value, and the calculation result is compared with the minimum attraction voltage. In actual project application, the method of directly comparing the input voltage with the minimum attraction voltage and the method of collecting the voltage signal for 10 ms for root mean square value calculation can be performed at the same time. According to which method calculates the result first, the attraction operation is performed based on the result.

[0136] In order to shorten the response time of the contactor in the attraction operation, the application also provides a method, when the power voltage is an alternating signal, the cumulative power of the contactor coil is calculated according to the preset interval time, when the cumulative power is less than the preset power threshold, the maximum value of the duty cycle of the PWM control signal is set to 100%, and when the cumulative power is greater than or equal to the preset power threshold, the duty cycle of the PWM control signal is adjusted according to the current value of the coil current signal, so that the contactor performs the attraction operation.

[0137] Among them, the preset interval time and the preset power threshold can be set by the user as needed.

[0138] In one example, since the power of the contactor coil L is equal to the product of the voltage signal and the coil current signal, the preset interval time is set to 0.2ms, the power of the contactor coil is calculated every 0.2ms, and the calculation results are accumulated every time to obtain the cumulative power of the contactor coil, when the cumulative power is less than the preset power threshold, the maximum value of the duty cycle of the PWM control signal is set to 100%, and preferably, the switch tube Q1 can be driven by the PWM control signal with a duty cycle of 100%, which can make the current of the contactor coil L increase rapidly, thereby shortening the response time of the contactor in the attraction operation, or the switch tube Q1 can be driven by the PWM control signal with a duty cycle of 98%, which can make the current of the contactor coil L increase rapidly. The user can set the duty cycle of the PWM control signal as needed, which is not limited in the application.

[0139] When the cumulative power is greater than or equal to the preset power threshold, the PWM control signal with a duty cycle of 100% does not need to be driven, and the duty cycle of the PWM control signal is adjusted according to the current value of the coil current signal, so that the contactor performs the attraction operation. When the contactor performs the attraction operation and the attraction maintenance operation, the frequency of the PWM control signal is adjusted according to the voltage value of the voltage signal, and the opening time, the opening time length, the closing time and the closing time length of the PWM control signal are adjusted to keep the current value of the coil current signal as a constant current value.

[0140] Since the greater the voltage value of the voltage signal, the shorter the time of the PWM control signal with a duty cycle of 100%, the time of the PWM control signal with a duty cycle of 100% corresponding to the same input voltage can be compared to determine the change of the internal resistance of the contactor coil L due to temperature. If the time of the PWM control signal with a duty cycle of 100% corresponding to the same input voltage becomes longer, the duty cycle of the PWM control signal can be adjusted in the later stage to compensate for the influence of the internal resistance of the contactor coil L due to temperature.

[0141] The application also provides a substrate, comprising: the contactor control circuit as described above.

[0142] The application also provides a contactor, comprising the substrate as described above.

[0143] Finally, it should be noted that the above embodiments are merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A contactor control circuit, characterized by, The contactor control circuit comprises a contactor coil, a voltage acquisition circuit, a current acquisition circuit, a switch tube, a PWM drive circuit and a master control circuit; The first end of the contactor coil is connected to an input voltage, the second end of the contactor coil is electrically connected to the second end of the switch tube, the first end of the switch tube is electrically connected to the input end of the current acquisition circuit, and the control end of the switch tube is electrically connected to the output end of the PWM drive circuit; the input end of the voltage acquisition circuit is connected to the input voltage, and the output end of the voltage acquisition circuit is electrically connected to the first end of the master control circuit; the input end of the PWM drive circuit is electrically connected to the second end of the master control circuit, and the output end of the current acquisition circuit is electrically connected to the third end of the master control circuit; The voltage acquisition circuit is configured to sample the input voltage to obtain a voltage signal; The master control circuit is configured to output a PWM control signal when the voltage value of the voltage signal is greater than a minimum attraction voltage; The PWM drive circuit is configured to output a PWM drive signal according to the PWM control signal to drive the switch tube, so that the contactor performs an attraction operation; The current acquisition circuit is configured to sample a current flowing through the contactor coil to obtain a coil current signal when the PWM drive signal drives the switch tube to be turned on; The master control circuit is further configured to adjust the frequency of the PWM control signal, and adjust the opening time, the opening duration, the closing time and the closing duration of the PWM control signal according to the voltage value of the voltage signal, so that the current value of the coil current signal remains a constant current value, when the contactor performs an attraction and maintenance operation, wherein the opening duration is the duration of turning on the PWM control signal, and the closing duration is the duration of turning off the PWM control signal.

2. The contactor control circuit of claim 1, wherein, The current acquisition circuit comprises a first diode, a first resistor, a second resistor and a first capacitor; The anode of the first diode is electrically connected to the first end of the first resistor, the first end of the second resistor and the first end of the switch tube respectively; The second end of the second resistor is electrically connected to the first end of the first capacitor and the third end of the master control circuit respectively; The cathode of the first diode, the second end of the first resistor and the second end of the first capacitor are all grounded.

3. The contactor control circuit of claim 1, wherein, The voltage acquisition circuit comprises a third resistor, a fourth resistor and a fifth resistor; The first end of the third resistor is connected to the input voltage, the second end of the third resistor is electrically connected to the first end of the fourth resistor, and the second end of the fourth resistor is electrically connected to the first end of the fifth resistor and the first end of the master control circuit respectively; The second end of the fifth resistor is grounded.

4. The contactor control circuit of claim 1, wherein, The contactor control circuit further comprises a control power supply circuit, an EMC circuit, a rectifier circuit, a freewheeling circuit and a fast release circuit; An input end of the control power supply circuit is connected to the input voltage, and a first output end of the control power supply circuit is electrically connected to a fourth end of the main control circuit; a second output end of the control power supply circuit is electrically connected to a power supply end of the PWM drive circuit; An input end of the EMC circuit is used to connect to a power supply voltage, an output end of the EMC circuit is electrically connected to an input end of the rectifier circuit, and an output end of the rectifier circuit is electrically connected to a first end of the freewheeling circuit and a first end of the contactor coil, respectively; A second end of the freewheeling circuit is electrically connected to a first end of the fast release circuit, a second end of the fast release circuit is electrically connected to a second end of the switch tube, and a third end of the fast release circuit is electrically connected to a fifth end of the main control circuit; The control power supply circuit is used to supply power to the main control circuit and the PWM drive circuit; The EMC circuit is used to perform anti-interference processing on the connected power supply voltage; The rectifier circuit is used to rectify the power supply voltage; The freewheeling circuit is used to provide a current path for the contactor coil when the switch tube is turned off, so that the contactor coil is freewheeled. The fast release circuit is used to provide a current path for the contactor coil according to the control signal provided by the fifth end of the main control circuit when the switch tube is turned off, so that the contactor coil is freewheeled; and is also used to provide a current consumption path for the contactor coil according to the control signal provided by the fifth end of the main control circuit when the voltage value of the voltage signal is less than the minimum release voltage, so that the contactor coil is released.

5. A contactor control method characterized by, The contactor control method is applied to the contactor control circuit of any one of claims 1-4; The input voltage is voltage-sampled to obtain a voltage signal; When the voltage value of the voltage signal is greater than the minimum attraction voltage, a PWM control signal is outputted; According to the PWM control signal, a PWM drive signal is outputted to drive the switch tube, so that the contactor performs attraction operation; When the PWM drive signal drives the switch tube to be turned on, the current flowing through the contactor coil is sampled to obtain a coil current signal; When the contactor performs attraction maintenance operation, the frequency of the PWM control signal is adjusted according to the magnitude of the voltage value of the voltage signal, and the opening time, the opening duration, the closing time and the closing duration of the PWM control signal are adjusted, so that the current value of the coil current signal remains a constant current value, wherein the opening duration is the duration of turning on the PWM control signal, and the closing duration is the duration of turning off the PWM control signal.

6. The contactor control method according to claim 5, wherein The adjustment of the frequency of the PWM control signal according to the magnitude of the voltage value of the voltage signal when the contactor performs attraction maintenance operation includes: The voltage value of the voltage signal is divided into a preset number of voltage value intervals when the contactor performs attraction maintenance operation; For any voltage value interval, the frequency of the corresponding PWM control signal is set.

7. The contactor control method according to claim 5, wherein The opening time, the opening duration, the closing time and the closing duration of the PWM control signal are adjusted to keep the current value of the coil current signal as a constant current value, including: When the power voltage is an alternating current signal: The opening time of the PWM control signal is the zero-crossing point of the alternating current signal, and the closing time of the PWM control signal is the peak point of the alternating current signal; According to the voltage value of the voltage signal, the opening duration and the closing duration of the PWM control signal are adjusted; When the power voltage is a direct current signal: The opening time of the PWM control signal is a first fixed time, and the closing time of the PWM control signal is a second fixed time; According to the voltage value of the voltage signal, the opening duration and the closing duration of the PWM control signal are adjusted.

8. The contactor control method according to claim 7, wherein The method further includes: When the power voltage is an alternating current signal: If the effective value of the alternating current signal in 1 / 4 cycle is greater than the preset multiple of the minimum attraction voltage, the PWM control signal is output; or, the cumulative power of the contactor coil is calculated at a preset interval time, and when the cumulative power is less than a preset power threshold, the maximum value of the duty cycle of the PWM control signal is set to 100%; when the cumulative power is greater than or equal to the preset power threshold, the duty cycle of the PWM control signal is adjusted according to the current value of the coil current signal, so that the contactor performs attraction operation.

9. A substrate, characterized by, Including: The contactor control circuit according to claims 1-4.

10. A contactor characterized by comprising: Including: The substrate according to claim 9.

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