Magnetic core driver capable of simultaneously transmitting power and signal

Abstract

The invention discloses a magnetic core driver capable of simultaneously transmitting power and signals. The magnetic core driver comprises a signal conversion unit, a signal processing unit and a signal processing unit, wherein the signal conversion unit is used for generating signals and power supply driving switch signals; the volt-second integral balance unit is used for calculating the width of the driving pulse so as to achieve rapid magnetic balance; the magnetic core driving unit is used for driving a power output structure of the pulse transformer; and the signal restoring unit is used for separating the power transmission part from the signal and restoring the signal. On the basis that rapid magnetic balance is achieved on one magnetic core, power and signal transmission is carried out at the same time. In the field of power driving, the driving performance of the MOSFET and the IGBT is greatly improved, and the system structure is simplified to the greatest extent. In the field of signal transmission application, an external power supply is not needed, and the system transmission structure can be greatly simplified. The system is suitable for integrated application and reduces system size.

Description

Technical Field

[0001] The invention relates to the field of driving and signal transmission of high-frequency magnetic core transformers. Background Art

[0002] With the rapid development of semiconductor technology, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, power field effect transistor) and IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) have been widely used.

[0003] The control gate of high-power MOSFET and IGBT is equivalent to a capacitor. In high-power MOSFET and IGBT high-voltage switch applications, more high-speed and high-power switches require isolated drivers. The driving mode using magnetic core isolation is a recognized safe driving mode. Its main feature is the passive structure, which makes it still very viable in many safety application fields. However, due to the leakage inductance of the magnetic core, the transmission delay and rise rate are limited. The magnetic field requires a positive and negative balance, which greatly limits its application.

[0004] Therefore, the sampling signal isolation and power supply separation structure improves the driving speed and power, allowing the signal to propagate quickly. However, the power supply structure still needs to be implemented through magnetic core isolation, and its isolation degree has not been improved. It's just that the structure is more complicated. From the perspective of signal transmission, this structure is no different from the conventional signal transmission structure.

[0005] Figure 1 , is the structure of this signal transmission and power transmission. The system can sometimes be very complex, and the signal can be direct signal transmission or modulated signal propagation.

[0006] Figure 2 In the prior art, an IGBT driver uses a pulse modulation structure because the switch signal covers DC to AC. This structure seriously affects the transmission rate and is only suitable for low-speed transmission.

[0007] Figure 3 A signal transmission structure of the prior art uses a digital isolation or optical coupling isolation structure to achieve high speed. If high power and timely driving are required, the additional post-stage driving increases the delay.

[0008] Figure 4 In the prior art, in fixed duty cycle transmission applications, there are examples of using magnetic core pulse signals to provide power supply and signal transmission as shown. At this time, part of the leading edge pulse transmission power needs to be occupied, and strict control is required during startup and shutdown. There are great hidden dangers. At the same time, the driving speed is not fast and DC signals cannot be transmitted.

[0009] Figure 5 In the transmission of low-speed, slowly changing pulse signals, there was once a scheme that used magnetic core signals to transmit power and signals at the same time. Since the self-balancing characteristics of the magnetic core itself were used to balance the volt-second integral, when the signal changed, the magnetic core could not be balanced in time, resulting in the signal transmission pulse out of control and failure. Few people used it.

[0010] Figure 6 , the core balance in the universal bridge balanced output structure. Since the driving waveforms in both directions are consistent, the core VS integral is the same, and the capacitor also plays a certain balancing role. Since the capacitor has an energy storage function, it needs to be carefully controlled during dynamic changes, otherwise the core imbalance will cause signal amplitude failure.

[0011] The emergence of magnetic core drivers has made the VS integral active balancing technology of magnetic cores possible. Summary of the invention

[0012] The problem to be solved by the present invention is to provide a magnetic core driver that transmits power and signals simultaneously, so as to overcome the complex system and slow speed in the existing power drive and signal drive, achieve a simple structure, have no special requirements for signals, and be suitable for integration.

[0013] To achieve the above object, the technical solution of the present invention provides a magnetic core driver that transmits power and signals simultaneously. The driver comprises:

[0014] Oscillator unit: generates a pulse signal with a certain duty cycle internally, and the pulse width meets the power transmission requirements;

[0015] A volt-second integration control unit is connected to the self-oscillator and the signal input, and is used to achieve the magnetic balance of the magnetic core as quickly as possible through active control in time after the pulse signal is generated;

[0016] Special core drive unit: connected to the integral control unit signal, used for transmitting transformer flux balance and signal transmission through a special control structure;

[0017] Signal sampling and power supply interface unit: connected to the secondary of the transmission transformer, realizing power conversion and signal acquisition conversion at the same time;

[0018] Preferably, the oscillator unit has a duty cycle of 1 / 4 (the ratio of the on-time to the oscillator period is Ton / T=1 / 4). It can be 1 / 3 to 1 / 5, depending on the recovery voltage.

[0019] Preferably, the volt-second integration control unit controls the magnetic recovery time of the magnetic core through an internal integrator, and the integrator can be in various forms, such as an analog integrator or a digital integrator.

[0020] Preferably, the volt-second integration control unit samples the edges of the input signal on and off to quickly reset the oscillator to achieve the purpose of modulation and form a pulse cluster. The starting leading edge of the oscillator pulse cluster represents the leading and trailing edges of the input signal. The rise or fall of the signal is determined by the flip change of the signal and then by the level. The pulse cluster itself does not represent the high or low state of the signal.

[0021] Preferably, the theoretical maximum operating frequency of the signal of the volt-second integration control unit can reach the oscillation frequency of the pulse cluster.

[0022] Preferably, the dedicated magnetic core driving unit adopts a dedicated structure in which a switch tube and a diode are connected in series, which can quickly provide a recovery path for the magnetic field.

[0023] Preferably, the signal sampling and power supply interface unit satisfies both energy transmission and signal transmission. Its energy transmission does not depend on the presence or absence of a signal. Both AC and DC signals can be demodulated.

[0024] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0025] It can meet the transmission of DC signals and AC digital signals. With the use of a dedicated magnetic core drive structure and the addition of active VS integral control, the signal frequency can be equal to the modulation frequency, and the operating frequency is higher. There is no limit on the narrowest pulse. Power and signal transmission are achieved through a magnetic core. The volume can be miniaturized through integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a commonly used transmission structure in the prior art;

[0027] Figure 2 It is a schematic diagram of the modulation signal pulse transmission of the prior art;

[0028] Figure 3 A transmission schematic diagram of a digital isolator in the prior art;

[0029] Figure 4 A functional block diagram for transmitting power at the forefront of the prior art;

[0030] Figure 5 It is a solution technology using passive magnetic recovery technology;

[0031] Figure 6 Bridge drive structure, which is a conventional magnetic balance output structure;

[0032] Figure 7 It is a schematic diagram of the implementation principle of the present invention;

[0033] Figure 8 After the signal comes, the polarity of the hysteresis loop changes

[0034] Fig. 9 Duty cycle requirements for volt-second integration;

[0035] Fig.10 A duty cycle 1 / 4 oscillator structure;

[0036] Fig.11 An integrating structure that controls the core energy recovery by integrating the VS of the conduction level.

[0037] Fig.12 Block diagram of the dedicated core driver used

[0038] Fig.13 correspond Fig.12 (1) Switch driving waveform and signal relationship;

[0039] Fig.14 A block diagram of output energy and signal sampling and signal restoration;

[0040] Fig.15 A push-pull structure for output energy and signal sampling; DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] Figure 7 , schematic diagram of the active magnetic balance control structure in the embodiment.

[0043] Figure 8 , after the signal comes, the polarity of the hysteresis loop changes. The energy transfer is unipolar. After the signal comes, the polarity of the energy transfer shifts from the 1st quadrant to the 3rd quadrant, symmetrical with the origin.

[0044] Fig. 9 , VS integral duty cycle requirements. Signal sampling is achieved through level comparison. In order to offset the false operation caused by the transformer distributed parameters, the VS integral voltage level should be significantly lower than the transformer output level. Therefore, the core duty cycle must be less than 50%. When the signal pulse width (positive or negative) is less than the power transmission pulse width (Ton), it is possible that the magnetic recovery time is greater than the set recovery time. In order to meet the extreme requirements of extremely narrow and wide duty cycles, the reverse recovery integral of VS should meet the requirement of being greater than 2 times the VS conduction integral to ensure the balance of VS within one cycle. Therefore, the actual power output duty cycle must be less than 1 / 4 (if the narrowest pulse width of the signal is wider, the duty cycle can be increased).

[0045] Fig.10, pulse frequency generator. To ensure that the signal duty cycle is effective between 0 and 100%, the recommended duty cycle is not greater than 1 / 4. If the duty cycle is too small, the output power transmission capacity will be affected. When the energy transmission meets the requirements, the higher the oscillation frequency, the higher the signal output frequency. This can be achieved with a simple 555 circuit. The pulse frequency generator can be one or two (one for the low level signal and one for the high level signal).

[0046] Fig.11 , use the comparator to judge the zero crossing, and realize the simple VS integral switch control. The resistor matching is used to adjust the time constant. The counter structure can also be used for zero crossing judgment.

[0047] Fig.12 There are many structures that can be used for special core drivers. The figure lists two typical structures. (1) is a bridge structure, and (2) is a push-pull structure. The upper half bridge or the lower half bridge can transmit energy independently. Therefore, the high and low levels of the signal can be obtained by whether the upper and lower half bridges are working. (1) The switch tube and the voltage regulator tube are connected in series. The volt-second integral voltage is determined by the voltage regulator voltage, and the excitation energy is also absorbed by the voltage regulator tube. This solution has large losses and slightly complicated control. The advantage is that the primary is a set of coils, the structure is simple, and the switch tube has a low withstand voltage. (2) The switch tube and the diode are connected in series. The volt-second integral voltage is determined by the transformer ratio, and the excitation energy is returned to the power supply side, which is relatively simple to control. The disadvantage is that the withstand voltage of the volt-second integral control tube is higher.

[0048] Fig.13 , when taking Fig.12 (1) During configuration, the relationship between the drive waveforms and signals of each switch.

[0049] Fig.14 , a block diagram of output energy and signal sampling and signal restoration. A bridge rectifier structure is used. Through two transistors, the current of each rectification cycle is sampled as a signal state judgment. Then, the pulse signal is restored through an RS trigger or a window comparator. The window comparator structure is used in the figure.

[0050] Fig.15 , another output energy and signal sampling and signal restoration diagram. It adopts a full-wave rectifier structure and a comparator structure. By sampling the high and low output voltage of the transformer and comparing it with the comparator threshold, the modulated pulse signal is input into the RS trigger to restore the pulse signal.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A core driver for transmitting power and signal simultaneously, characterized in that: The driver comprises: Oscillator unit: generates a pulse signal with a specific duty cycle internally, meeting the requirements of signal and power transmission; A volt-second integration control unit is connected to the self-oscillator and the signal input, and is used to achieve magnetic balance of the magnetic core within one cycle through active control in time after the pulse signal is generated; Special core drive unit: connected with the integral control unit signal, realizes transformer flux balance and signal transmission through a special circuit structure; Signal sampling and power supply interface unit: connected to the secondary of the transmission transformer, realizing power conversion and signal acquisition conversion functions at the same time.

2. The core driver for transmitting power and signals as claimed in claim 1, characterized in that The oscillator unit has a fixed frequency and a fixed duty cycle.

3. The core driver for transmitting power and signals as claimed in claim 1, characterized in that The volt-second (VS) integral control unit will dynamically adjust the VS integral in time with the signal input to control the switch drive of the power tube.

4. The core driver for transmitting power and signals as claimed in claim 1, characterized in that A specially designed core drive unit combining MOS and diode is used to directly drive the core transformer and meet the VS integral regulation requirements.

5. The core driver for transmitting power and signals as claimed in claim 1, characterized in that: The signal sampling and power supply interface unit has its input end directly connected to the magnetic core transformer, and directly separates the power and signal pulses through the combination of a triode and a diode.

6. The core driver for transmitting power and signals as claimed in claim 1, characterized in that: The signal restoration unit directly realizes normal signal demodulation output through a simple comparator structure or a trigger structure.

7. The oscillator according to claim 2, characterized in that The oscillator has a duty cycle of 1 / 3 to 1 / 4 (depending on the narrowest pulse limit and the highest magnetic recovery voltage).

8. The volt-second integration control unit as claimed in claim 3 performs time integration on the driving signal, and controls the volt-second (VS) integration of each cycle through a specially formulated output logic according to the timing of the occurrence of the reference signal.

Images