A dual PWM modulation non-inductive charger

Abstract

The present invention discloses a non-inductive charger with dual PWM modulation. The charger includes an MCU control circuit, a dual PWM high-frequency switching circuit, a high-frequency power transformer circuit, and a C filter output circuit; the control mode of the dual PWM high-frequency switching circuit is to add an intermittent PWM on the basis of the traditional power PWM modulation, thereby forming a dual PWM modulation. Due to the application of dual PWM, the L filter inductor may not be required in the output rectifier filter circuit, thereby saving costs and increasing the reliability of the charger. In addition, due to the application of dual PWM, intermittent charging pulses are generated, so such a charger is conducive to desulfurization, reducing hydrogen evolution, reducing water loss, controlling thermal balance, enhancing the electrochemical reaction of the battery, extending the service life of the battery, increasing the charging power to shorten the charging time, improving the battery capacity, and increasing the range of the electric vehicle.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to chargers. Background Art

[0002] For the convenience of description, the present invention uses the following abbreviations:

[0003] "Power PWM" refers to traditional power pulse width modulation;

[0004] "Intermittent PWM" refers to the generalized pulse width modulation used to generate intermittent pulses as agreed in the present invention;

[0005] "Intermittent coefficient" refers to the coefficient of the intermittent PWM duty cycle as the charging time changes as stipulated in the present invention;

[0006] The "intermittent index package" refers to the initial Ton and Toff coefficients of the dual PWM in each charging state specified in the present invention, which is an array.

[0007] Figure 4 This is a traditional single PWM modulated charger power circuit module diagram. As can be seen from the figure, the transformer is single PWM modulated, and is based on Figure 1 The power PWM mode works continuously. The basic hardware structure of current chargers is similar. In this traditional charger field, they all have a common feature - single PWM modulation. During the entire charging process, the input control of the high-frequency power transformer is completed by a switch tube. The control of this switch tube adopts a power PWM pulse width modulation. Its problem is that the cycle is very short (less than 50us), and it works continuously, and it is impossible to achieve continuous long-cycle intermittent pulses. This is not conducive to the maintenance of lead-acid batteries or maintenance-free batteries. Some chargers only add a simple charging shutdown operation at the beginning and end stages, which is also called pulse charging, but the effect is obviously very poor.

[0008] Figure 6 The output filter circuit of the single charger is an LC filter with a large L filter inductor, which increases the cost and weight of the charger and reduces the reliability and charging efficiency of the charger. Summary of the invention

[0009] The purpose of the present invention is to solve the above two deficiencies: one is to enhance the maintenance of the battery; the other is to save L filter inductance, reduce the cost of the charger, and improve the reliability of the charger.

[0010] The charger includes an MCU control circuit, a dual PWM high-frequency switch circuit, a high-frequency power transformer circuit, and a C filter output circuit.

[0011] The MCU control circuit is connected to the dual PWM high-frequency switch circuit and is the management center of the entire charger.

[0012] The dual PWM high frequency switch circuit is connected to the high frequency power transformer circuit. The primary switch of the high frequency power transformer is completely controlled by the MCU through the dual PWM high frequency switch circuit.

[0013] The dual PWM high frequency switch circuit is a high frequency PWM pulse width adjustment circuit composed of MOS tube or IGBT. The control mode of the dual PWM high frequency switch circuit is to add an intermittent PWM on the basis of traditional power PWM modulation, thereby forming dual PWM modulation.

[0014] The dual PWM modulation means that in one cycle, Ton is the charging time, working with traditional power PWM, which belongs to the mode of traditional charger, and Toff is the off time, and the power PWM is completely turned off.

[0015] The dual PWM modulation adds an intermittent PWM modulation during the entire charging process. According to the different charging stages and the charging characteristics of the battery, the intermittent PWM parameters are adjusted to obtain different intermittent charging pulses, thereby extending the battery life, increasing the charging power to shorten the charging time, increasing the battery capacity, and increasing the mileage of the electric vehicle. This solves the problems encountered by the above-mentioned traditional chargers.

[0016] During the entire charging process, the output current is continuously collected. At this time, the MCU control circuit is connected to the current collection circuit. The charger current limit value is determined by the average value of the current collection circuit in the entire cycle.

[0017] During the entire charging process, the temperature inside and outside the charger must be continuously collected. At this time, the MCU control circuit is connected to the temperature collection circuit. The temperature collection circuit contains the temperature of the internal power components and the temperature of the external battery. Because these temperature values ​​are important parameters of the dual PWM. The temperature of the external battery is mainly used for temperature compensation of the charger.

[0018] The high-frequency power transformer circuit is connected to the C filter output circuit. The material used for the high-frequency power transformer is ferrite.

[0019] The C filter output circuit may not include an L filter inductor. Figure 7The invention is a dual PWM modulated charger output C filter circuit. Compared with the traditional charger, the invention has significant differences in the control of the transformer and the structure of the output rectifier filter. Due to the application of dual PWM, the output rectifier filter circuit does not need the L filter inductor, thereby saving costs, increasing the reliability of the charger, improving the charging efficiency, and reducing the weight of the charger.

[0020] When the discharge function is required, the MCU control circuit is connected to the discharge circuit. When the negative pulse function is required, the MCU control circuit is connected to the negative pulse circuit.

[0021] The temperature acquisition circuit includes the internal radiator temperature of the charger and the external battery temperature.

[0022] The effects of the present invention are as follows: it is beneficial to desulfurization, reduce hydrogen evolution, reduce water loss, control heat balance, enhance the electrochemical reaction of the battery, increase charging power, shorten charging time, improve battery capacity, and increase the driving range of the electric vehicle. Moreover, the output filter circuit of the charger of the present invention does not need an L filter inductor, which saves costs, increases charger reliability, improves charging efficiency, and reduces the weight of the charger. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the traditional power pwm timing diagram;

[0024] Figure 2 This is the dual pwm timing diagram;

[0025] Figure 3 This is a dual pwm workflow diagram;

[0026] Figure 4 This is a module diagram of the charger power circuit with single PWM modulation;

[0027] Figure 5 This is a module diagram of the charger power circuit with dual PWM modulation;

[0028] Figure 6 Output LC filter circuit for single charger;

[0029] Figure 7 Output C filter circuit for dual PWM modulated charger. DETAILED DESCRIPTION

[0030] Figure 5 The module diagram of the charger power circuit with dual PWM modulation includes AC / DC conversion circuit 1, front-stage rectification and PFC circuit 2, high-frequency power transformer circuit 3, C filter output circuit 4, dual PWM high-frequency switch circuit 5, and mcu6 control circuit. The working process of the present invention is described in detail below in conjunction with the accompanying drawings.

[0031] The AC / DC1 conversion circuit connects the front-stage rectifier and PFC circuit 2. The function of the AC / DC1 conversion circuit is to convert the AC power of the mains into DC. The AC source includes 220v single-phase input or 380v three-phase input. Its core component is the rectifier bridge.

[0032] The front-stage rectifier circuit and PFC2 are connected to the AC / DC conversion circuit 1 and the high-frequency power transformer circuit 3. The front-stage rectifier and PFC circuit 2 convert the pulsed DC obtained in the front stage into DC with smaller ripple. Its core component is the filter capacitor. For applications with high requirements, its core circuit is the PFC circuit.

[0033] The high-frequency power transformer circuit 3 is connected to the front-stage rectifier and PFC circuit 2, the dual PWM high-frequency switch circuit 5, and the C filter output circuit 4. The high-frequency power transformer circuit 3 is a device for converting the power between the front and rear poles of the charger, and the front and rear poles are electrically isolated. The switch of the high-frequency power transformer 3 circuit is controlled by the dual PWM high-frequency switch circuit 5.

[0034] The C filter output circuit 4 is connected to the high-frequency power transformer circuit 3. The input of the C filter output circuit 4 comes from the high-frequency power transformer circuit 3, and its output is connected to the battery. The C filter output circuit 4 converts the pulse voltage output by the high-frequency power transformer circuit 3 into a voltage with a small ripple. Figure 7 . Figure 7 It is a dual PWM modulated charger output C filter circuit, and Figure 6 Compared with the single charger output LC filter circuit shown in FIG, the L filter inductor is directly removed. The core component of the C filter output circuit 4 is the electrolytic capacitor. The traditional filter circuit is an LC filter circuit, and its core components are the inductor and the electrolytic capacitor.

[0035] However, it should be noted that the C filter output circuit 4 of the present invention may not contain an L filter inductor. If an L filter inductor must be added, the system can still work. However, it is futile to maliciously add this L filter inductor to circumvent the protection of this patent.

[0036] The dual PWM high frequency switch circuit 5 is connected to the high frequency power transformer circuit 3 and the mcu control circuit 6. The working mode of the dual PWM high frequency switch circuit 5 is dual pwm modulation, which is described in detail as follows:

[0037] Figure 1This is a traditional power PWM timing diagram. In a cycle t, t1 is the switch on time, and t2 is the switch off time. There are two control modes when charging: one is to adjust the size of t1 while keeping the cycle t constant, which is called width modulation; the other is to adjust the size of t while keeping t1 constant, which is called frequency modulation. Frequency modulation and width modulation are basically pulse width modulation, which is actually duty cycle adjustment. Here, the size of t is in the microsecond uS level, and this is where the high-frequency switching power supply comes from.

[0038] The feature of the present invention is that a layer of intermittent PWM is added on this basis. Figure 2 This is a dual PWM timing diagram. In one cycle, Ton is the charging time, working with power PWM, the power tube is constantly switching, which belongs to the category of traditional chargers; Toff is the off time, the power PWM is completely off, and the charger has no power output. During the Toff time, two functions can be added according to cost and customer requirements: discharge function and negative pulse function. However, these two functions are completed instantly, and the time is microsecond uS level. Therefore, there can be three actions during the Toff time: complete shutdown, discharge, and negative pulse.

[0039] The Toff time can be very long, generally 10ms to 3s, which is more than 1000 times the traditional pulse interval time, and the entire charging process is based on this mechanism. This can fully meet the technical requirements of the battery and achieve the purpose of maintaining the battery.

[0040] During the charging process, the intermittent PWM adjustment process of the present invention is: according to the charging state of the battery, the battery temperature, the battery characteristics, the charger power, etc., the values ​​of Ton and Toff are adjusted in real time. In the actual software programming process, Ton and Toff are derived from an intermittent index package, and the intermittent index packages of different models of chargers and different specifications of batteries from different manufacturers are all different.

[0041] Figure 3 This is a dual PWM workflow diagram, and the implementation process of the present invention is described in detail using this as an example.

[0042] According to the output voltage, output current, internal and external temperatures, etc. of the charger, the above intermittent index package is obtained for each battery.

[0043] Generally, the entire charging process of a battery is divided into five stages: pre-charging - constant current - trickle current - constant voltage - floating charge. There are also three basic stages: constant current - constant voltage - floating charge. There are also more detailed ones, which means there are more charging stages. But no matter how many stages are used for charging, the operating process of the present invention is: at each new charging stage, an intermittent base is first assigned to Ton and Toff, and then the intermittent coefficient is adjusted as the voltage and temperature of the battery increase. Figure 3 Just an example.

[0044] When entering the pre-charge state for the first time, the program assigns the interval base value, Ton=Kon1, Toff=Koff1. Then gradually adjust Ton and Toff, and the voltage gradually increases.

[0045] When the constant current stage is first entered, the program assigns the intermittent base value, Ton=Kon2, Toff=Koff2. Then Ton and Toff are gradually adjusted, and the voltage gradually increases.

[0046] When the trickle current stage is first entered, the program assigns the intermittent base value, Ton=Kon3, Toff=Koff3. Then Ton and Toff are gradually adjusted, and the voltage gradually increases.

[0047] When the constant voltage stage is first entered, the program assigns the intermittent base value, Ton=Kon4, Toff=Koff4. Then gradually adjust Ton and Toff, and the current gradually decreases until it reaches the rated value.

[0048] When entering the floating charge stage for the first time, the program assigns the intermittent base value, Ton=Kon5, Toff=Koff5. Then gradually adjust Ton and Toff, and the battery temperature gradually decreases until the rated time charging is completed.

[0049] In the above adjustment process, the description of the traditional power PWM is omitted because it does not belong to the innovation of the present invention.

[0050] See Figure 5 , the mcu control circuit 6 is connected to the dual PWM high-frequency switching circuit 5, which is the control center of the charger.

[0051] The above embodiments and descriptions are only for explaining the principle of the present invention and one example thereof. There may be various changes and improvements based on this principle, and these changes and improvements are all within the scope of protection of the present invention.

Claims

1. A dual PWM modulation non-inductive charger, characterized in that: The charger comprises an MCU control circuit, a dual PWM high-frequency switch circuit, a high-frequency power transformer circuit and a C filter output circuit; the MCU control circuit is connected to the dual PWM high-frequency switch circuit; the dual PWM high-frequency switch circuit is connected to the high-frequency power transformer circuit; the high-frequency power transformer circuit is connected to the C filter output circuit; the control mode of the dual PWM high-frequency switch circuit is to add an intermittent PWM on the basis of the traditional power PWM modulation, thereby forming a dual PWM modulation; The MCU control circuit modulates the dual PWM high-frequency switch circuit based on the intermittent index package; the intermittent index package is an array containing intermittent coefficients and intermittent bases, and its data comes from chargers of different models and batteries of different specifications; at each new charging stage, the intermittent base is the initial value of Ton and Toff, and the intermittent coefficient is the coefficient of the intermittent PWM changing with the charging time; the MCU control circuit uses the intermittent index package to set different Ton and Toff and modulates the voltage and current of the charger in combination with the intermittent coefficient, so as to realize the five-stage precise charging of the battery: pre-charging, constant current, trickle current, constant voltage and floating charge; The C filter output circuit does not contain an L filter inductor; The dual PWM modulation means that in one cycle, Ton is the charging time, working with traditional power PWM, which belongs to the mode of traditional charger, and Toff is the off time, and the power PWM is completely turned off.

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