A DC circuit of an electromagnetic coil and a device

Abstract

The present invention discloses a DC circuit of an electromagnetic coil and a device. The DC circuit of the electromagnetic coil is connected to a load and an MCU, and includes a control module, a voltage circuit module, and a current circuit module. The control module performs frequency modulation on an input power supply according to a reference voltage fed back by the voltage circuit module, and outputs the modulated voltage to the voltage circuit module and the load. The voltage circuit module generates an output voltage after constant current of the modulated voltage and transmits it to the MCU, performs voltage division sampling on the output voltage, and feeds back the reference voltage to the control module. The current circuit module samples the current flowing through the load and outputs a corresponding sampled voltage to the MCU. By the constant current of the voltage circuit module and the modulation of the control module, the present invention makes the output voltage constant. The current circuit module uses the load as a large inductor to sample the large current flowing through the load, ensuring accurate sampling while eliminating the need to set up an existing large inductor, saving the space of the circuit board.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and more particularly to an electromagnetic coil DC circuit and device. Background Art

[0002] As Figure 1 shown, the existing buck circuit is usually composed of devices such as a switch, an inductor, a diode, and a capacitor. In a low-power power supply circuit, the current flowing through the inductor L is usually relatively small, the package of the inductor L is small, and the space occupied on the PCB board is small (maximum 12×12); if the current in the load circuit is greater than or equal to 5A, or even as high as 10A, the inductor L (usually a chip inductor) cannot be applied to the large-current situation, and a large ferrite-wound inductor needs to be used. The large inductor has a large package and occupies a large space on the PCB board, and the inductance value error is also large. Moreover, the load (usually an electromagnet coil) is also equivalent to an inductor. The simultaneous presence of two inductors not only wastes cost but also wastes space. Summary of the Invention

[0003] In view of the various deficiencies of the prior art, the inventor has researched and designed an electromagnetic coil DC circuit and device through long-term practice. While ensuring accurate sampling, there is no need to set a large inductor in the existing circuit, saving the space of the PCB.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An electromagnetic coil DC circuit, connecting a load and an MCU, comprising a control module, a voltage circuit module, and a current circuit module;

[0006] The control module performs frequency modulation on the input power supply according to the reference voltage fed back by the voltage circuit module, and outputs the modulated voltage to the voltage circuit module and the load;

[0007] The voltage circuit module generates an output voltage after constant current on the modulated voltage and transmits it to the MCU, performs voltage division sampling on the output voltage, and feeds back the reference voltage to the control module;

[0008] The current circuit module samples the current flowing through the load and outputs the corresponding sampling voltage to the MCU.

[0009] Further, in the electromagnetic coil DC circuit, the control module includes a switching tube, a diode, and a power supply chip; the drain of the switching tube inputs the input power supply, the gate of the switching tube is connected to the SW pin of the power supply chip; the source of the switching tube is connected to the negative pole of the diode, one end of the load, and the voltage circuit module; the positive pole of the diode is grounded, and the VFB pin of the power supply chip is connected to the voltage circuit module.

[0010] Further, in the DC circuit of the electromagnetic coil, the power supply chip outputs a corresponding modulation signal according to the reference voltage to control the on or off of the switching transistor, and performs frequency modulation on the input power supply.

[0011] Further, in the DC circuit of the electromagnetic coil, the voltage loop module includes a constant current source, a first inductor, a first capacitor, a first resistor, and a second resistor; the input end of the constant current source is connected to the source electrode of the switching transistor and the negative electrode of the diode, and the output end of the constant current source is connected to one end of the first inductor; the other end of the first inductor is the output end, connected to one end of the first capacitor, one end of the first resistor, and the voltage sampling pin of the MCU; the other end of the first resistor is connected to one end of the second resistor and the VFB pin of the power supply chip; the other end of the second resistor is connected to the other end of the first capacitor, the current loop module, and the ground.

[0012] Further, in the DC circuit of the electromagnetic coil, the first inductor is a chip inductor, and is packaged in 0805 or 1206.

[0013] Further, in the DC circuit of the electromagnetic coil, the voltage output by the switching transistor is first made constant current by the constant current source and then stores energy in the first inductor to generate an output voltage. The first resistor and the second resistor perform voltage division sampling on the output voltage and feedback the reference voltage to the power supply chip.

[0014] Further, in the DC circuit of the electromagnetic coil, the current loop module includes a second capacitor and a third resistor. One end of the second capacitor is connected to the other end of the load, one end of the third resistor, and the current sampling pin of the MCU; the other end of the second capacitor is connected to the other end of the third resistor, the other end of the second resistor, and the ground.

[0015] Further, in the DC circuit of the electromagnetic coil, the current in the voltage loop module is a constant current of 100 mA, and the current in the current loop module is greater than or equal to 5 A.

[0016] In the second aspect of the embodiments of the present invention, a device is provided, including a host, and a circuit board is provided inside the host. Among them, an MCU, a load, and the DC circuit of the electromagnetic coil are provided on the circuit board;

[0017] The DC circuit of the electromagnetic coil modulates the input power supply, outputs an output voltage with constant current and stable voltage, samples the current flowing through the load, and feeds back the corresponding sampling voltage to the MCU. The MCU calculates the power of the load according to the output voltage and the sampling voltage.

[0018] The beneficial effects of the present invention are:

[0019] Through the constant current of the voltage loop module and the modulation of the control module, the output voltage is made to be constantly regulated; the current loop module uses the load (with inductive characteristics) as a large inductor to sample the large current flowing through the load. While ensuring accurate sampling, there is no need to set the large inductor in the existing loop, saving the space of the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic circuit diagram of an existing buck circuit;

[0021] Figure 2 is a structural block diagram of the device in an embodiment of the present invention;

[0022] Figure 3 is a schematic circuit diagram of the DC circuit of the electromagnetic coil in an embodiment of the present invention;

[0023] Figure 4 is a schematic waveform diagram of the output voltage in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0025] Please refer to Figure 2 and Figure 3 simultaneously. Inside the housing of the host of the device provided by the embodiment of the present invention, there is a circuit board. An electromagnetic coil DC circuit, an MCU, and a load L2 are provided on the circuit board. The electromagnetic coil DC circuit is connected to the MCU and the load L2 and is also externally connected to a power adapter; the electromagnetic coil DC circuit modulates the input power VIN provided by the power adapter, outputs a constant current and regulated output voltage U0, samples the current flowing through the load and feeds back the corresponding sampling voltage ADC_J to the MCU, and the MCU calculates the power of the load according to the output voltage U0 and the sampling voltage ADC_J.

[0026] The electromagnetic coil DC circuit is mainly applied to power drive on a bike trainer. Then the device can be various devices such as a bike trainer, and the load L2 is an electromagnet coil with inductive characteristics. The MCU is a prior art. Only the pin connections related to this embodiment are shown here. The connections of other pins of the MCU are prior art and will not be elaborated here.

[0027] The DC circuit of the electromagnetic coil includes a control module 10, a voltage circuit module 20, and a current circuit module 30; the control module 10 is connected to the voltage circuit module 20 and the load L2, and the current circuit module 30 is connected to the load and the MCU. The control module 10 performs frequency modulation (i.e., PWM modulation) on the input power supply VIN according to the reference voltage FB fed back by the voltage circuit module 20, and outputs the modulated voltage V0 to the voltage circuit module 20 and the load L2; the voltage circuit module 20 generates an output voltage U0 after constant current on the modulated voltage V0 and transmits it to the MCU, performs voltage division sampling on the output voltage U0, and feeds back the reference voltage FB to the control module 10; the current circuit module 30 samples the current flowing through the load and feeds back the corresponding sampled voltage to the MCU.

[0028] The control module 10 includes a switching transistor Q1, a diode D1, and a power supply chip U1; the drain of the switching transistor Q1 inputs the input power supply VIN (the drain is connected to the positive output of the power adapter), the gate of the switching transistor Q1 is connected to the SW pin of the power supply chip U1; the source of the switching transistor Q1 is connected to the negative electrode of the diode D1, one end of the load L2, and the voltage circuit module 20; the positive electrode of the diode D1 is grounded, and the VFB pin of the power supply chip U1 is connected to the voltage circuit module 20. The negative output of the power adapter is grounded.

[0029] Among them, the power supply chip U1 is an existing DCDC (DC) power supply chip (the specific model is not limited), and only the pin connections related to this embodiment are shown here. The connections of other pins are prior art and will not be elaborated here. The power supply chip U1 outputs a corresponding modulation signal (such as Figure 3 the periodic pulse waveform shown) to control the switching transistor Q1 (preferably an NMOS transistor) to conduct or cut off, so as to perform frequency modulation on the input power supply VIN, adjust the output voltage U0 of the voltage circuit module 20, make the voltage value of the output voltage U0 reach a fixed value (such as stabilize to 12V), and output a stable DC voltage source (i.e., the output voltage U0).

[0030] The voltage circuit module 20 includes a constant current source 21, a first inductor L1, a first capacitor C1, a first resistor R1, and a second resistor R2; the input end of the constant current source 21 is connected to the source of the switching transistor Q1 and the negative electrode of the diode D1, and the output end of the constant current source 21 is connected to one end of the first inductor L1; the other end of the first inductor L1 is the output end (for transmitting the output voltage U0), connected to one end (positive electrode) of the first capacitor C1, one end of the first resistor R1, and the voltage sampling pin of the MCU; the other end of the first resistor R1 is connected to one end of the second resistor R2 and the VFB pin of the power supply chip U1; the other end of the second resistor R2 is connected to the other end of the first capacitor C1, the current circuit module 30, and the ground.

[0031] Among them, the first inductor L1 is a surface mount inductor, and packages such as 0805 or 1206 can be used. The constant current source 21 can use a corresponding constant current source device or constant current chip to make the output current value constant at 100 mA. The voltage loop starts from the output of the switching transistor Q1, and successively passes through the constant current source 21, the first inductor L1, the first resistor R1, the second resistor R2 (the first capacitor C1 is in parallel with R1 and R2), and finally returns to the power supply chip U1; specifically: the voltage V0 output by the switching transistor Q1 is first made constant current by the constant current source 21 and then stores energy in the first inductor L1 to generate the output voltage U0 (the waveform is as Figure 4 shown), the first resistor R1 and the second resistor R2 divide the output voltage U0 for voltage sampling, and feedback the reference voltage FB to the power supply chip U1 for voltage value adjustment. The first capacitor C1 is used to filter the output voltage U0, and the voltage value of the output voltage U0 is determined by the voltage loop module 20 and is a fixed value; the MCU collects the voltage value of the output voltage U0 for the calculation of the power of subsequent products.

[0032] The current loop module 30 includes a second capacitor C2 and a third resistor R3. One end (positive pole) of the second capacitor C2 is connected to the other end of the load L2, one end of the third resistor R3, and the current sampling pin (ADC pin) of the MCU; the other end of the second capacitor C2 is connected to the other end of the third resistor R3, the other end of the second resistor R2, and the ground.

[0033] Among them, the third resistor R3 is a sampling resistor; the current loop starts from the output of the switching transistor Q1, successively passes through the load L2, the third resistor R3 (the second capacitor C2 is in parallel with the third resistor R3), and finally is sampled by the MCU; specifically: the voltage V0 after being amplitude modulated by the modulation signal is output from the switching transistor Q1, transmitted to the load L2, and the sampled voltage ADC_J is output after being sampled by the third resistor R3 to the MCU; the MCU can obtain the current I flowing through the load L2 by reading the voltage across the third resistor R3 and combining the resistance value of the third resistor R3 (known), I = ADC_J / R3, where ADC_J represents the voltage value of the sampled voltage and R3 represents the resistance value of the third resistor, realizing current sampling. The magnitude of the current in the current loop can be set according to the device requirements and can be greater than or equal to 5 A (the magnitude of the current is not limited), and such a large current passes through this current loop to provide energy for the load L2.

[0034] In this embodiment, when the current is large (greater than or equal to 5A), the current loop is used, and the load (electromagnet coil) is used to replace the inductor in the existing loop; when the current is small, the voltage loop is used, and a 100mA chip inductor (i.e., the first inductor L1) is used to provide the reference voltage FB. In this way, the existence of the existing high-power inductor is reduced, and the voltage in the current loop can be deduced from the output voltage in the voltage loop, providing accurate data for accurately calculating the power of the device. Specifically: according to the voltage value of the output voltage U0, the voltage value V across the load L2 can be deduced, V = 0.94Uo, where 0.94 is a reference coefficient (obtained through measurement and data analysis). By obtaining the accurate current I and voltage V in the load loop, the MCU can calculate the power (P = V×I) and the internal resistance of the load in the load loop, monitor the internal resistance of the load, and then deduce the heat loss. Temperature compensation is performed on the loss caused by the resistance characteristics of the load according to the heat loss, improving the power accuracy of the device (which can be improved to 1% through testing), so as to accurately calculate the power of the device.

[0035] In summary, the DC loop and device of the electromagnetic coil provided by the present invention adopt a dual-closed-loop design of a large-current current loop and a small-current voltage loop. Utilizing the inductance characteristics of the load (electromagnet coil), the load is used to replace the inductor L in the existing buck loop in the current loop, solving the problem that the existing inductor is not suitable for large currents, meeting the usage conditions of large currents, and also saving costs and the space occupied by the circuit board by eliminating the existing inductor; at the same time, a voltage loop is added and a constant-current design is carried out in the voltage loop. The current meets 100mA, and only a 0805-package chip inductor is used for the inductor in the voltage loop. The chip inductor only supports the loop design of the feedback voltage source, enabling the output voltage to be accurately stepped down to 12V. While meeting the accurate voltage, the space of the circuit board is also reduced.

[0036] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An electromagnetic coil DC circuit, connected to a load and an MCU, is characterized in that, It includes a control module, a voltage loop module and a current loop module; The control module performs frequency modulation on the input power supply according to the reference voltage fed back by the voltage loop module, and outputs the modulated voltage to the voltage loop module and the load; The voltage loop module performs constant current on the modulated voltage to generate an output voltage and transmits it to the MCU, divides the output voltage for sampling and feeds back the reference voltage to the control module; The current loop module samples the current flowing through the load and outputs the corresponding sampled voltage to the MCU; The voltage loop module includes a constant current source, a first inductor, a first capacitor, a first resistor and a second resistor; the input end of the constant current source is connected to the control module, and the output end of the constant current source is connected to one end of the first inductor; the other end of the first inductor is the output end, connected to one end of the first capacitor, one end of the first resistor and the voltage sampling pin of the MCU; the other end of the first resistor is connected to one end of the second resistor and the control module; the other end of the second resistor is connected to the other end of the first capacitor, the current loop module and the ground; At low current, it goes through the voltage loop, and the voltage loop outputs from the control module, passes through the constant current source, the first inductor, the first resistor, the second resistor in sequence, and returns to the control module; At high current, it goes through the current loop, and the current loop outputs from the control module, passes through the load and the current loop module in sequence, and is sampled by the MCU; The first inductor is a chip inductor, and the load is an electromagnet coil.

2. The DC circuit of the electromagnetic coil according to claim 1, wherein The control module includes a switching tube, a diode and a power supply chip; the drain of the switching tube inputs the input power supply, the gate of the switching tube is connected to the SW pin of the power supply chip; the source of the switching tube is connected to the negative pole of the diode, one end of the load and the voltage loop module; the positive pole of the diode is grounded, and the VFB pin of the power supply chip is connected to the voltage loop module.

3. The DC circuit of the electromagnetic coil according to claim 2, wherein, The power supply chip outputs a corresponding modulation signal according to the reference voltage to control the switching tube to conduct or cut off, and performs frequency modulation on the input power supply.

4. The DC circuit of the electromagnetic coil according to claim 2, characterized in that, The first inductor uses a 0805 or 1206 package.

5. The DC circuit of the electromagnetic coil according to claim 2, characterized in that, The voltage output by the switching tube is first constant-current by the constant current source, stores energy in the first inductor to generate an output voltage, and the first resistor and the second resistor divide the output voltage for sampling, and feed back the reference voltage to the power supply chip.

6. The DC circuit of the electromagnetic coil according to claim 2 or 4, characterized in that, The current loop module includes a second capacitor and a third resistor, one end of the second capacitor is connected to the other end of the load, one end of the third resistor and the current sampling pin of the MCU; the other end of the second capacitor is connected to the other end of the third resistor, the other end of the second resistor and the ground.

7. The DC circuit of the electromagnetic coil according to claim 6, characterized in that, The current in the voltage loop module is a constant current of 100 mA, and the current in the current loop module is greater than or equal to 5 A.

8. A device, comprising a main unit, wherein a circuit board is provided in the main unit, characterized in that, The circuit board is provided with an MCU, a load and the electromagnetic coil DC circuit according to any one of claims 1-7; The electromagnetic coil DC circuit modulates the input power supply, outputs a constant current and regulated output voltage, samples the current flowing through the load and feeds back the corresponding sampled voltage to the MCU, and the MCU calculates the power of the load according to the output voltage and the sampled voltage.

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