Source-carrying system starting device, method and source-carrying system

Abstract

The present application discloses a source-load system startup device, method and source-load system, including a DC power supply terminal, a switch module, a voltage sampling module and a control module, wherein the control module includes a DSP and a drive circuit, and the DSP is provided with a comparator, a direct proportional function unit and a carrier unit, and the DSP calculates the slope of the direct proportional function according to the target charging time and the charging control algorithm, and adjusts the duty cycle of the switch module according to the slope of the direct proportional function so that the actual charging time of the filter capacitor meets the target charging time. The present application can realize the pre-charging of the filter capacitor, and is not limited by the ambient temperature, there is no additional power consumption after the source-load system is normally started, and the charging time of the filter capacitor can be controlled.

Description

Technical Field

[0001] The present application relates to the field of source-carrying systems, and in particular to a source-carrying system starting device, method and source-carrying system. Background Art

[0002] In the source load system, a filter capacitor is set between the front-stage output and the back-stage circuit. At the moment of power-on, since the filter capacitor is not charged, the large-capacitance filter capacitor is almost short-circuited. If it is started directly, there will be a large surge current, which will seriously damage the life of the filter capacitor. Therefore, it is necessary to pre-charge the filter capacitor before starting to suppress the surge current.

[0003] In the related art, reference Figure 3 As shown, taking the boost circuit as an example, the existing pre-charging method is to connect a negative temperature coefficient (NTC-Negative Temperature Coefficient) resistor in series at the AC input end, using the characteristics of the NTC resistor having a large resistance at room temperature and a small resistance at high temperature. At the beginning of startup, the NTC resistor is large, which has the effect of current limiting. After a period of startup, as the NTC resistor itself consumes power and generates heat, its own resistance decreases, reducing the additional power consumption, and the high-power power supply enters a normal working state. However, this method is only applicable to environments with low external temperatures. Before the source-load system is started, if the external ambient temperature is high, the NTC resistor has a very small resistance and cannot play a role in current limiting and suppressing surge current. Even if the NTC resistor has a low impedance at high temperatures, there is still a certain amount of additional power consumption. In addition, since the capacitance of the filter capacitor in different source-load systems is different, the optimal charging time of the filter capacitor is also different. Although the pre-charging method in the related art can extend the charging time of the filter capacitor, it cannot accurately control the charging time of the filter capacitor. Summary of the invention

[0004] The present application proposes a source-load system startup device, method and source-load system, which can realize pre-charging of the filter capacitor, are not limited by the ambient temperature, have no additional power consumption after the source-load system is normally started, and can control the charging time of the filter capacitor.

[0005] According to the source-load system starting device of the first aspect of the embodiment of the present application, a filter capacitor is connected, and the filter capacitor is arranged between the front-stage output terminal and the rear-stage circuit, including: a DC power supply terminal for inputting a DC power supply; a switch module, one end of the switch module is connected to the DC power supply terminal, and the other end of the switch module is connected to the positive electrode of the filter capacitor through a first resistor; a voltage sampling module, the input end of the voltage sampling module is used to collect the voltage of the filter capacitor; a control module, the control module includes a DSP and a drive circuit, the DSP is provided with a comparator, a direct proportional function unit and a carrier unit, the direct proportional function unit is connected to the in-phase end of the comparator, the carrier unit is connected to the inverting end of the comparator, the output end of the comparator is connected to the PWM signal output end of the DSP, the PWM signal output end of the DSP is connected to the control end of the switch module through the drive circuit, the parameter setting end of the DSP is used to input a target charging time, the DSP is used to calculate the slope of the direct proportional function according to the target charging time and the charging control algorithm, and adjust the duty cycle of the switch module according to the slope of the direct proportional function so that the actual charging time of the filter capacitor meets the target charging time.

[0006] According to some embodiments of the present application, the calculation formula of the charging control algorithm is:

[0007] ;

[0008] Wherein, Tch is the target charging time, R1 is the resistance of the first resistor, C1 is the capacitance of the filter capacitor, k is the slope of the proportional function, V0 is the output voltage of the DC power supply, V1 is the sampling voltage of the filter capacitor, and the amplitude of the carrier in the carrier unit is 1. , , fs is the switching frequency of the switch module.

[0009] According to some embodiments of the present application, the voltage sampling module includes an operational amplifier and an ADC module, the non-inverting end of the operational amplifier is connected to the positive electrode of the filter capacitor, the inverting end of the operational amplifier is connected to the negative electrode of the filter capacitor, the output end of the operational amplifier is connected to the input end of the ADC module, and the output end of the ADC module is connected to the voltage feedback end of the DSP.

[0010] According to some embodiments of the present application, a host computer is also included, and the host computer is connected to the parameter setting end.

[0011] According to the second aspect of the present application, the source load system startup method includes the following steps:

[0012] Obtaining a target charging time, where the target charging time is used to indicate a preset charging time of the filter capacitor;

[0013] Substituting the target charging time into the charging control algorithm, the slope of the direct proportional function is obtained;

[0014] The duty cycle of the switch module is adjusted according to the slope output of the proportional function, so that the actual charging time of the filter capacitor meets the target charging time.

[0015] The source-carrying system according to the third aspect of the present application includes the above-mentioned source-carrying system starting device. The source-carrying system starting device, method and source-carrying system according to the embodiment of the present application have at least the following beneficial effects:

[0016] In the implementation mode of the present application, when the source load system is turned on, the DSP controls the switch module to be turned on through the driving circuit, and the DC power supply end charges the filter capacitor through the first resistor. The DSP calculates the slope of the proportional function according to the target charging time and the charging control algorithm, and outputs a driving waveform with a gradually increasing duty cycle according to the slope of the proportional function to adjust the duty cycle of the switch module so that the actual charging time of the filter capacitor meets the target charging time. The DSP obtains the voltage across the filter capacitor through the voltage sampling module, and when the filter capacitor is full, the DSP controls the switch module to disconnect. The present application can realize the pre-charging of the filter capacitor, reduce the impact current received by the rear-stage circuit at startup, and is not limited by the ambient temperature. There is no additional power consumption after the source load system is normally started, and the charging time of the filter capacitor can be accurately controlled.

[0017] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0019] Figure 1 This is a circuit schematic diagram of the source-carrying system starting device in an embodiment of the present application;

[0020] Figure 2 This is a flow chart of a method for starting a source load system in an embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of a BOOST circuit with an NTC resistor in the related art. DETAILED DESCRIPTION

[0022] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0023] In the description of the present application, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0024] In the description of this application, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0025] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0026] Reference Figure 1 As shown, a source load system starting device is connected to a filter capacitor C1, and the filter capacitor C1 is arranged between the front-stage output terminal and the rear-stage circuit, including: a DC power supply terminal, a switch module S1, a voltage sampling module and a control module. Specifically, the DC power supply terminal is used to input a DC power supply, and in this embodiment, the DC power supply terminal adopts a DC high-voltage source; one end of the switch module S1 is connected to the DC power supply terminal, and the other end of the switch module S1 is connected to the positive electrode of the filter capacitor C1 through a first resistor, and in this embodiment, the first resistor is a resistor R1; the input end of the voltage sampling module is used to collect the voltage of the filter capacitor C1. The control module includes a DSP and a driving circuit. A comparator, a proportional function unit and a carrier unit are provided in the DSP. The proportional function unit is connected to the in-phase end of the comparator, the carrier unit is connected to the inverting end of the comparator, the output end of the comparator is connected to the PWM signal output end of the DSP, the PWM signal output end of the DSP is connected to the control end of the switch module through the driving circuit, the parameter setting end of the DSP is used to input the target charging time, the DSP is used to calculate the slope of the proportional function according to the target charging time and the charging control algorithm, and adjust the duty cycle of the switch module according to the slope of the proportional function so that the actual charging time of the filter capacitor C1 meets the target charging time.

[0027] In this implementation, the front-stage output end may be the output end of a rectifier bridge, and the rear-stage circuit may be a BOOST circuit or other circuits.

[0028] It should be noted that if the switch module S1 is always turned on, the voltage V0 directly charges the filter capacitor C1 through the resistor R1. If the filter capacitor C1 is charged to the voltage V1, the charging time of the filter capacitor C1 is 5*R1*C1. , , then the charging time That is, within 50ms, the current will decay rapidly from 31A to 0, and this period of time can easily burn out the switch module S1 and the resistor R1. Therefore, the present application prolongs the charging time by controlling the on-duty cycle of the switch module S1.

[0029] In order to achieve precise control of the charging time, the DSP obtains a target charging time through the parameter setting end. The target charging time can be input by the host computer or devices such as buttons and touch screens. The DSP calculates the slope of the direct proportional function based on the target charging time and the charging control algorithm, and adjusts the duty cycle of the switch module according to the slope of the direct proportional function so that the actual charging time of the filter capacitor C1 meets the target charging time, thereby achieving precise control of the charging time.

[0030] In the implementation mode of the present application, when the source load system is turned on, the DSP controls the switch module S1 to be turned on through the driving circuit, and the DC power supply end charges the filter capacitor C1 through the resistor R1. The DSP calculates the slope of the proportional function according to the target charging time and the charging control algorithm, and outputs a driving waveform with a gradually increasing duty cycle according to the slope of the proportional function to adjust the duty cycle of the switch module so that the actual charging time of the filter capacitor C1 meets the target charging time. The DSP obtains the voltage across the filter capacitor C1 through the voltage sampling module, and the DSP controls the switch module to disconnect when the filter capacitor C1 is full. The present application can realize the pre-charging of the filter capacitor C1, reduce the impact current received by the rear-stage circuit at startup, and is not limited by the ambient temperature. There is no additional power consumption after the source load system is normally started, and the charging time of the filter capacitor C1 can be accurately controlled.

[0031] It should be noted that the filter capacitor C1 is fully charged refers to being charged to an appropriate value. This appropriate value is pre-set in the DSP as a parameter. Different filter capacitors C1 have different rated voltages, so the appropriate value for full charge is also different. The DSP obtains the voltage across the filter capacitor C1 in real time through the voltage sampling module. When the filter capacitor C1 is charged to an appropriate value, the switch module S1 is disconnected to avoid current backflow and continuous consumption of the resistor R1.

[0032] Among them, the calculation formula of the charging control algorithm is:

[0033]

[0034] Wherein, Tch is the target charging time, R1 is the resistance of the first resistor, C1 is the capacitance of the filter capacitor C1, k is the slope of the proportional function, V0 is the output voltage of the DC power supply end, V1 is the sampling voltage of the filter capacitor C1, and in this application, the charging control algorithm also needs to meet the following conditions: the amplitude of the carrier in the carrier unit is 1, , , fs is the switching frequency of the switch module.

[0035] It should be noted that This means that the target charging time needs to be less than the time it takes for the proportional function to reach the carrier amplitude. This means that the slope k of the direct proportional function needs to be much smaller than the switching frequency of the switch module S1.

[0036] The derivation process of the charging control algorithm is described below, as follows:

[0037] Assume that the carrier frequency is 10kHz, the amplitude is 1, the voltage V0 at the DC output end is 500V, the target charging voltage is 400V, C1=1000uF, and R1=100Ω.

[0038] When the switch module S1 is continuously turned on, the relationship between the voltage of V1 and VO is:

[0039] ;

[0040] The expression of the direct proportional function is y=kt, the sawtooth wave carrier frequency is fs, the period is Ts, Ts=1 / fs, and the amplitude is 1, so the sawtooth wave slope is fs=1 / Ts.

[0041] The first cycle: The carrier is always greater than the direct proportional function, so we can get:

[0042] ;

[0043] In the second period, according to the direct proportional function expression, we can get:

[0044] ;

[0045] Solving the above equations, we get the conduction time:

[0046] ;

[0047] In the third period, according to the direct proportional function expression, we can get:

[0048] ;

[0049] Solving the above equations, we get the conduction time:

[0050] ;

[0051] In the Nth cycle, the value of the proportional function must still be less than the amplitude of the sawtooth wave carrier, 1. According to the proportional function expression, we can get:

[0052] ;

[0053] Solving the above equations together, we get:

[0054] ;

[0055] Therefore, the total on-time is:

[0056] ;

[0057] By transforming the above formula into an arithmetic progression, we can get:

[0058] ;

[0059] because Much larger than k, fs-k≈fs, n is numerically large, n-1≈n;

[0060] so:

[0061] ;

[0062] If the target voltage is V1 and the DC voltage is VO, we can get:

[0063] ;

[0064] So the required Ton is:

[0065] ;

[0066] The two equations are equal, and we get the period number n;

[0067] ;

[0068] Solving for n, we get:

[0069] ;

[0070] Therefore, the expression of the target charging time is:

[0071] ;

[0072] The following is a verification explanation. After calculation, when the target charging time is 2.53s, k=0.05 is calculated, as follows;

[0073] ;

[0074] After simulation, when the slope k=0.05, the actual charging time of the filter capacitor C1 is 2.53s, which is equal to the target charging time.

[0075] It should be understood that, since the capacitance of the filter capacitor C1 in different source-load systems is different, the optimal charging time of the filter capacitor in different source-load systems is also different. If the charging time is too fast, the capacitor may burn out easily. If the charging time is too slow, the startup time of the source-load system may be too long, which may also affect the user experience. Therefore, it is necessary to shorten the charging time as much as possible while avoiding capacitor burning and ensuring the safety and stability of the circuit. That is, it is necessary to adjust the charging time according to different filter capacitors and different input voltages to achieve the best effect. Although the duty cycle of the PWM signal output by the control module can be directly adjusted to achieve the adjustment of the charging time, if it is directly controlled, the duty cycle output waveform of the control module needs to be set according to different stages, such as the duty cycle at startup, the duty cycle when half of the startup, and the duty cycle when the capacitor is fully charged, etc. The debugging process is very troublesome and difficult to achieve. However, the present application only needs to calculate the optimal charging time according to the model of the filter capacitor C1 and the voltage of the DC voltage source, and then input the optimal charging time as the target charging time into the DSP. The DSP will automatically calculate the slope of the proportional function corresponding to the target charging time, and then perform duty cycle control on the switch module S1. There is no need to manually calculate the duty cycle or slope k value, which is convenient for debugging and easy to implement.

[0076] In this embodiment, the DSP can accurately obtain the slope k according to the target charging time through the built-in charging control algorithm, and then control the conduction of the switch module S1 through the slope k. The switch module S1 can use a MOS tube or other conduction devices that can control the duty cycle.

[0077] In some embodiments of the present application, the voltage sampling module includes an operational amplifier and an ADC module, the in-phase terminal of the operational amplifier is connected to the positive electrode of the filter capacitor C1, the inverting terminal of the operational amplifier is connected to the negative electrode of the filter capacitor C1, the output terminal of the operational amplifier is connected to the input terminal of the ADC module, and the output terminal of the ADC module is connected to the voltage feedback terminal of the DSP.

[0078] In this implementation, the voltage of the filter capacitor C1 is collected by an operational amplifier and an ADC module, so that the sampling accuracy can be improved.

[0079] In some implementations of the present application, a host computer is also included, and the host computer is connected to the parameter setting terminal.

[0080] In this implementation, the target charging time is set by the host computer, which can improve the flexibility of parameter setting.

[0081] In the above implementation, the host computer can be connected to the parameter setting terminal of the DSP via the SPI bus or other communication interface.

[0082] refer to Figure 2As shown, the present application also relates to a source load system startup method, comprising the following steps:

[0083] S101, obtaining a target charging time, where the target charging time is used to indicate a preset charging time of the filter capacitor C1;

[0084] S102, substituting the target charging time into the charging control algorithm to obtain the slope k of the direct proportional function;

[0085] S103 , adjusting the duty cycle of the switch module according to the slope output of the direct proportional function, so that the actual charging time of the filter capacitor C1 meets the target charging time.

[0086] The source-carrying system starting method of the embodiment of the present application has the same working principle and process as the source-carrying system starting device, and will not be described in detail here.

[0087] The present application also relates to a source-carrying system, including the source-carrying system starting device of the above embodiment.

[0088] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A source load system starting device, connected to a filter capacitor, the filter capacitor is arranged between the front stage output terminal and the rear stage circuit, It is characterized in that include: DC power supply terminal, used for inputting DC power; A switch module, one end of which is connected to the DC power supply end, and the other end of which is connected to the positive electrode of the filter capacitor via a first resistor; A voltage sampling module, the input end of which is used to collect the voltage of the filter capacitor; A control module, the control module includes a DSP and a driving circuit, the DSP is provided with a comparator, a direct proportional function unit and a carrier unit, the direct proportional function unit is connected to the non-phase end of the comparator, the carrier unit is connected to the inverting end of the comparator, the output end of the comparator is connected to the PWM signal output end of the DSP, the PWM signal output end of the DSP is connected to the control end of the switch module through the driving circuit, the parameter setting end of the DSP is used to input the target charging time, the DSP is used to calculate the slope of the direct proportional function according to the target charging time and the charging control algorithm, and adjust the duty cycle of the switch module according to the slope of the direct proportional function so that the actual charging time of the filter capacitor meets the target charging time.

2. The source-carrying system starting device according to claim 1, It is characterized in that The calculation formula of the charging control algorithm is: ； Wherein, Tch is the target charging time, R1 is the resistance of the first resistor, C1 is the capacitance of the filter capacitor, k is the slope of the proportional function, V0 is the output voltage of the DC power supply, V1 is the sampling voltage of the filter capacitor, and the amplitude of the carrier in the carrier unit is 1. , , fs is the switching frequency of the switch module.

3. The source-carrying system starting device according to claim 1, It is characterized in that The voltage sampling module includes an operational amplifier and an ADC module, the in-phase end of the operational amplifier is connected to the positive electrode of the filter capacitor, the inverting end of the operational amplifier is connected to the negative electrode of the filter capacitor, the output end of the operational amplifier is connected to the input end of the ADC module, and the output end of the ADC module is connected to the voltage feedback end of the DSP.

4. The source-carrying system starting device according to claim 1, It is characterized in that It also includes a host computer, which is connected to the parameter setting end.

5. A source-on-board system starting method applied to the source-on-board system starting device according to any one of claims 1 to 4, It is characterized in that The following steps are involved: Obtaining a target charging time, where the target charging time is used to indicate a preset charging time of the filter capacitor; Substituting the target charging time into the charging control algorithm, the slope of the direct proportional function is obtained; The duty cycle of the switch module is adjusted according to the slope output of the proportional function, so that the actual charging time of the filter capacitor meets the target charging time.

6. A source-carrying system, It is characterized in that It comprises the source-carrying system starting device as described in any one of claims 1 to 4.

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